U.S. patent number 7,033,500 [Application Number 10/178,900] was granted by the patent office on 2006-04-25 for systems and methods using multiple solvents for the removal of lipids from fluids.
This patent grant is currently assigned to Lipid Sciences, Inc.. Invention is credited to David C. Bomberger, Bryan Chavez, Pablo E. Garcia, Eric Hegwer, Thomas P. Low, Ripudaman Malhotra, Jeffrey J. Shimon.
United States Patent |
7,033,500 |
Bomberger , et al. |
April 25, 2006 |
Systems and methods using multiple solvents for the removal of
lipids from fluids
Abstract
This invention is directed to systems and methods for removing
lipids from a fluid or from lipid-containing organisms from a
fluid, such as plasma. These systems combine a fluid with at least
one extraction solvent, which causes the lipids to separate from
the fluid or from the lipid-containing organisms. The separated
lipids are removed from the fluid. The at least one extraction
solvent is removed from the fluid or at least reduced to a
concentration enabling the fluid to be administered to a patient
without undesirable consequences. Once the fluid has been
processed, the fluid may be administered to a patient who donated
the fluid or to a different patient for therapy.
Inventors: |
Bomberger; David C. (Belmont,
CA), Chavez; Bryan (San Jose, CA), Garcia; Pablo E.
(Redwood City, CA), Hegwer; Eric (Menlo Park, CA), Low;
Thomas P. (Belmont, CA), Malhotra; Ripudaman (San
Carlos, CA), Shimon; Jeffrey J. (Mountain View, CA) |
Assignee: |
Lipid Sciences, Inc.
(Pleasanton, CA)
|
Family
ID: |
27540863 |
Appl.
No.: |
10/178,900 |
Filed: |
June 21, 2002 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20030150809 A1 |
Aug 14, 2003 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60346094 |
Jan 2, 2002 |
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60301112 |
Jun 25, 2001 |
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60301108 |
Jun 25, 2001 |
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60300927 |
Jun 25, 2001 |
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60301109 |
Jun 25, 2001 |
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Current U.S.
Class: |
210/321.79;
210/253; 210/257.2; 210/321.8; 210/649; 210/804; 210/806; 210/807;
604/5.03; 210/805; 210/650; 210/645; 210/263; 210/255; 210/252 |
Current CPC
Class: |
A61M
1/34 (20130101); A61M 1/3472 (20130101); A61M
1/3403 (20140204); B01D 61/362 (20130101); A61M
1/3616 (20140204); A61M 1/342 (20130101); A61M
1/3482 (20140204); A61M 1/3486 (20140204); A61M
1/3496 (20130101); A61M 2202/08 (20130101); A61M
2202/206 (20130101); A61M 2205/3331 (20130101); A61M
2205/3306 (20130101); A61M 2202/203 (20130101); A61M
2202/0456 (20130101); A61M 2205/3334 (20130101); A61M
1/3693 (20130101) |
Current International
Class: |
B01D
63/00 (20060101); C02F 1/44 (20060101) |
Field of
Search: |
;210/252,253,255,257.2,263,321.79,321.8,645,649,660,804-807
;604/5.03 |
References Cited
[Referenced By]
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Aug 2002 |
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WO |
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Primary Examiner: Walker; W. L.
Assistant Examiner: Menon; Krishnan S.
Attorney, Agent or Firm: Kilpatrick Stockton LLP
Parent Case Text
RELATED APPLICATIONS
This application claims the benefit of the filing dates of U.S.
Provisional Application No. 60/301,112, filed Jun. 25, 2001; U.S.
Provisional Patent Application No. 60/301,108, filed Jun. 25, 2001;
U.S. Provisional Patent Application No. 60/300,927, filed Jun. 25,
2001; U.S. Provisional Patent Application No. 60/301,109, filed
Jun. 25, 2001; and U.S. Provisional Patent Application No.
60/346,094, filed Jan. 2, 2002, all of which are incorporated by
reference herein.
Claims
We claim:
1. A device for removing at least one lipid from a fluid containing
lipids or lipid-containing organisms, comprising: a fluid source
containing the fluid and coupled to at least one hollow fiber
contactor; a first extraction solvent source containing a first
extraction solvent and coupled to the at least one hollow fiber
contactor; the at least one hollow fiber contactor that receives
the fluid from the fluid source and the first extraction solvent
from the first extraction solvent source, forming a first mixture
and dissolving at least a portion of the lipids; a second
extraction solvent source containing a second extraction solvent
and coupled to a first solvent removal apparatus; the first solvent
removal apparatus coupled to the at least one hollow fiber
contactor, wherein the first solvent removal apparatus receives the
first mixture from the at least one hollow fiber contactor and the
second extraction solvent from the second extraction solvent
source, forming a second mixture and dissolving additional lipids
and at least a portion of the first extraction solvent; and a
second solvent removal apparatus that is coupled to the first
solvent removal apparatus and receives the second mixture and
removes at least a portion of any remaining solvents from the
second mixture.
2. The device of claim 1, wherein the first solvent removal
apparatus comprises at least one hollow fiber contactor.
3. The device of claim 1, wherein the first solvent removal
apparatus comprises at least one drip through column.
4. The device of claim 3, wherein the first solvent removal
apparatus comprises at least one vortexer.
5. The device of claim 3, wherein the first solvent removal
apparatus comprises at least one centrifuge.
6. The device of claim 1, wherein first solvent removal apparatus
comprises at least one in-line static-mixer.
7. The device of claim 1, wherein the first solvent removal
apparatus comprises at least one vortexer.
8. The device of claim 1, wherein the second solvent removal
apparatus comprises at least one hollow fiber contactor.
9. The device of claim 8, wherein the second solvent removal
apparatus comprises at least two hollow fiber contactors coupled
together in parallel.
10. The device of claim 8, wherein the second solvent removal
apparatus comprises at least two hollow fiber contactors coupled
together in series.
11. A device for removing at least one lipid from a fluid
containing lipids or lipid-containing organisms, comprising: a
fluid source containing the fluid and coupled to a first apparatus;
a first extraction solvent source containing a first extraction
solvent and coupled to the first apparatus; the first apparatus
that receives the fluid from the fluid source and the first
extraction solvent from the first extraction solvent source,
forming a first mixture and dissolving at least a portion of the
lipids; a second extraction solvent source containing a second
extraction solvent and coupled to at least one hollow fiber
contactor; the at least one hollow fiber contactor coupled to the
first apparatus, wherein the at least one hollow fiber contactor
receives the first mixture from the first apparatus and the second
extraction solvent from the second extraction solvent source,
forming a second mixture and dissolving additional lipids and at
least a portion of the first extraction solvent; and a second
apparatus that is coupled to the at least one hollow fiber
contactor and receives the second mixture and removes at least a
portion of any remaining solvents from the second mixture.
12. The device of claim 11, wherein the first apparatus comprises
at least one hollow fiber contactor.
13. The device of claim 11, wherein the first apparatus comprises
at least one drip through column.
14. The device of claim 11, wherein the first apparatus comprises
at least one in-line static-mixer.
15. The device of claim 11, wherein the first apparatus comprises
at least one vortexer.
16. The device of claim 11, wherein the second apparatus comprises
at least one hollow fiber contactor.
17. The device of claim 16, wherein the second apparatus comprises
at least two hollow fiber contactors coupled together in
parallel.
18. The device of claim 16, wherein the second apparatus comprises
at least two hollow fiber contactors coupled together in series.
Description
FIELD OF THE INVENTION
The present invention relates to systems, apparatuses and methods
for the removal of lipids from fluids, especially blood plasma, or
from lipid-containing organisms, or both, using extraction
solvents. After being processed, the fluid may be administered to
an animal or human for therapeutic use such as treatment of
arteriosclerosis and atherosclerotic vascular diseases, removal of
fat within an animal or human, and reduction of infectivity of
lipid-containing organisms.
BACKGROUND OF THE INVENTION
Hyperlipidemia and Arteriosclerosis
Cardiovascular, cerebrovascular, and peripheral vascular diseases
are responsible for a significant number of deaths annually in many
industrialized countries. One of the most common pathological
processes underlying these diseases is arteriosclerosis.
Arteriosclerosis is characterized by lesions, which begin as
localized fatty thickenings in the inner aspects of blood vessels
supplying blood to the heart, brain, and other organs and tissues
throughout the body. Over time, these atherosclerotic lesions may
ulcerate, exposing fatty plaque deposits that may break away and
embolize within the circulation. Atherosclerotic lesions obstruct
the lumens of the affected blood vessels and often reduce the blood
flow within the blood vessels, which may result in ischemia of the
tissue supplied by the blood vessel. Embolization of
atherosclerotic plaques may produce acute obstruction and ischemia
in distal blood vessels. Such ischemia, whether prolonged or acute,
may result in a heart attack or stroke from which the patient may
or may not recover. Similar ischemia in an artery supplying an
extremity may result in gangrene requiring amputation of the
extremity.
For some time, the medical community has recognized the
relationship between arteriosclerosis and levels of dietary lipid,
serum cholesterol, and serum triglycerides within a patient's blood
stream. Many epidemiological studies have been conducted revealing
that the amount of serum cholesterol within a patient's blood
stream is a significant predictor of coronary disease. Similarly,
the medical community has recognized the relationship between
hyperlipidemia and insulin resistance, which can lead to diabetes
mellitus. Further, hyperlipidemia and arteriosclerosis have been
identified as being related to other major health problems, such as
obesity and hypertension.
Hyperlipidemia may be treated by changing a patient's diet.
However, use of a patient's diet as a primary mode of therapy
requires a major effort, on the part of patients, physicians,
nutritionists, dietitians, and other health care professionals and
thus undesirably taxes the resources of health professionals.
Another negative aspect of this therapy is that its success does
not rest exclusively on diet. Rather, success of dietary therapy
depends upon a combination of social, psychological, economic, and
behavioral factors. Thus, therapy based only on correcting flaws
within a patient's diet is not always successful.
In instances when dietary modification has been unsuccessful, drug
therapy has been used as an alternative. Such therapy has included
use of commercially available hypolipidemic drugs administered
alone or in combination with other therapies as a supplement to
dietary control. Hypolipidemic drugs have had varying degrees of
success in reducing blood lipid; however, none of the hypolipidemic
drugs successfully treats all types of hyperlipidemia. While some
hypolipidemic drugs have been fairly successful, the medical
community has not found any conclusive evidence that hypolipidemic
drugs cause regression of atherosclerosis. In addition, all
hypolipidemic drugs have undesirable side effects. As a result of
the lack of success of dietary control, drug therapy and other
therapies, atherosclerosis remains a major cause of death in many
parts of the world.
To combat this disturbing fact, a relatively new therapy has been
used to reduce the amount of lipid in patients for whom drug and
diet therapies were not sufficiently effective. This therapy,
referred to as plasmapheresis therapy or plasma exchange therapy,
involves replacing a patient's plasma with donor plasma or more
usually a plasma protein fraction. While having been fairly
successful, this treatment has resulted in complications due to
introduction of foreign proteins and transmission of infectious
diseases. Further, plasma exchange undesirably removes many plasma
proteins, such as very low-density lipoprotein (VLDL), low-density
lipoprotein (LDL), and high-density lipoprotein (HDL).
HDL is secreted from both the liver and the intestine as nascent,
disk-shaped particles that contain cholesterol and phospholipids.
HDL is believed to play a role in reverse cholesterol transport,
which is the process by which excess cholesterol is removed from
tissues and transported to the liver for reuse or disposal in the
bile. Therefore, removal of HDL from plasma is not desirable.
Other apheresis techniques exist that can remove LDL from plasma.
These techniques include absorption of LDL in heparin-agarose beads
(affinity chromatography), the use of immobilized LDL-antibodies,
cascade filtration absorption to immobilize dextran sulphate, and
LDL precipitation at low pH in the presence of heparin. Each method
removes LDL but not HDL.
LDL apheresis, however, has disadvantages. For instance,
significant amounts of plasma proteins in addition to LDL are
removed during apheresis. In addition, LDL apheresis must be
performed frequently, such as weekly, to obtain a sustained
reduction in LDL-cholesterol. Furthermore, LDL removal may be
counterproductive because low LDL levels in a patient's blood may
result in increased cellular cholesterol synthesis. Thus, removal
of LDL from a patient's blood may have negative side effects.
Yet another method of achieving a reduction in plasma cholesterol
in homozygous familial hypercholesterolemia, heterozygous familial
hypercholesterolemia and patients with acquired hyperlipidemia is
an extracorporeal lipid elimination process, referred to as lipid
apheresis. In lipid apheresis, blood is withdrawn from a patient,
the plasma is separated from the blood, and the plasma is mixed
with a solvent mixture. The solvent mixture extracts lipids from
the plasma. Thereafter, the delipidated plasma is recombined with
the patient's blood cells and returned to the patient.
More specifically, lipid apheresis results in the removal of fats
from plasma or serum. However, unlike LDL apheresis, the proteins
(apolipoproteins) that transport lipids remain soluble in the
treated plasma or serum. Thus, the apolipoproteins of VLDL, LDL and
HDL are present in the treated plasma or serum. These
apolipoproteins, in particular apolipoproteins Al from the
delipidated HDL in the plasma or serum, are responsible for the
mobilization of unwanted lipids or toxins, such as excessive
amounts of deposited lipids including cholesterol in arteries,
plaques, and excessive amounts of triglycerides, adipose tissue,
and fat soluble toxins present in adipose tissue. These excessive
amounts of lipids or toxins are transferred to the plasma or serum,
and then bound to the newly assembled apolipoproteins. Application
of another lipid apheresis procedure successively removes these
unwanted lipids or toxins from the plasma and thus the body. The
main advantage of this procedure is that LDL and HDL are not
removed from the plasma. Instead, only cholesterol, some
phospholipid and a considerable amount of triglycerides are
removed.
While lipid apheresis has the potential to overcome the
shortcomings of dietary control, drug therapy and other apheresis
techniques, existing apparatuses and methods for lipid apheresis do
not provide a sufficiently rapid and safe process. Thus, a need
exists for systems, apparatuses and methods capable of conducting
lipid apheresis more quickly than accomplished with conventional
equipment and methods.
Unfortunately, existing lipid apheresis systems suffer from a
number of disadvantages that limit their ability to be used in
clinical applications, such as in doctors' offices and other
medical facilities. One disadvantage is the explosive nature of the
solvents used to delipidate this plasma. If used in a continuous
system, these solvents are in close proximity to patients and
medical staff. Thus, it would be advantageous to limit this
exposure; however, this hazard is clearly present for the duration
of the delipidation process, which usually runs for several
hours.
Another disadvantage is the difficulty in removing a sufficient
amount of solvents from the delipidated plasma in order for the
delipidated plasma to be safely returned to a patient. In addition,
patients are subjected to an increased chance of prolonged exposure
to solvents in a continuous system. Furthermore, current techniques
do not provide for sequential multi-washes because the volume of
blood necessary for continuous processing using conventional
equipment requires removal of an amount of blood that would harm
the patient. In other words, conventional equipment does not allow
for automated continuous removal, processing and return of plasma
to a patient in a manner that does not negatively impact total
blood volume of the patient. While the long-term toxicity of
various extraction solvents is not known, especially when present
in the bloodstream, clinicians know that some solvents may cross
the blood-brain barrier. Furthermore, external contact with
solvents is known to cause clinical symptoms, such as irritation of
mucous membranes, contact dermatitis, headaches, dizziness and
drowsiness. Therefore, conventional equipment for lipid apheresis
is not adequate to conduct continuous processing of a patient's
blood.
Infectious Disease
While the medical community has struggled to develop cures for
hyperlipidemia and arteriosclerosis, it has likewise struggled in
its battle against infectious diseases. Infectious diseases are a
major cause of suffering and death throughout the world. Infectious
disease of varied etiology affects billions of animals and humans
each year and inflicts an enormous economic burden on society. Many
infectious organisms contain lipid as a major component of the
membrane that surrounds them. Three major classes of organisms that
produce infectious disease and contain lipid in their cell wall or
envelope include bacteria, viruses, and protozoa. Numerous bacteria
and viruses that affect animals and humans cause extreme suffering,
morbidity and mortality. Many bacteria and viruses travel
throughout the body in fluids, such as blood, and some reside in
plasma. These and other infectious agents may be found in other
fluids, such as peritoneal fluid, lymphatic fluid, pleural fluid,
pericardial fluid, cerebrospinal fluid, and in various fluids of
the reproductive system. Disease can be caused at any site bathed
by these fluids. Other bacteria and viruses reside primarily in
different organ systems or in specific tissues, where they
proliferate and enter the circulatory system to gain access to
other tissues and organs.
Infectious agents, such as viruses, affect billions of people
annually. Recent epidemics include the disease commonly known as
acquired immune deficiency syndrome (AIDS), which is believed to be
caused by the human immunodeficiency virus (HIV). This virus is
rapidly spreading throughout the world and is prevalent in various
sub-populations, including individuals who receive blood
transfusions, individuals who use needles contaminated with the
disease, and individuals who contact infected fluids. This disease
is also widespread in certain countries. Currently, no known cure
exists.
It has long been recognized that a simple, reliable and
economically efficient method for reducing the infectivity of the
HIV virus is needed to decrease transmission of the disease.
Additionally, a method of treating fluids of infected individuals
is needed to decrease transmission of the virus to others in
contact with these fluids. Furthermore, a method of treating blood
given to blood banks is needed to decrease transmission of the
virus through individuals receiving transfusions. Moreover, an
apparatus and method are needed for decreasing the viral load of an
individual or an animal by treating the plasma of that individual
and returning the treated plasma to the individual such that the
viral load in the plasma is decreased.
Other major viral infections that affect animals and humans
include, but are not limited to meningitis, cytomegalovirus, and
hepatitis in its various forms. While some forms of hepatitis may
be treated with drugs, other forms have not been successfully
treated in the past.
At the present time, most anti-viral therapies focus on preventing
or inhibiting viral replication by manipulating the initial
attachment of the virus to the T4 lymphocyte or macrophage, the
transcription of viral RNA to viral DNA and the assemblage of new
virus during reproduction. Such a focus has created major
difficulty with existing treatments, especially with regard to HIV.
Specifically, the high mutation rate of the HIV virus often renders
treatments ineffective shortly after application. In addition, many
different strains of HIV have already become or are becoming
resistant to anti-viral drug therapy. Furthermore, during
anti-viral therapy treatment, resistant strains of the virus may
evolve. Finally, many common therapies for HIV infection involve
several undesirable side effects and require patients to ingest
numerous pills daily. Unfortunately, many individuals are afflicted
with multiple infections caused by more than one infectious agent,
such as HIV, hepatitis and tuberculosis. Such individuals require
even more aggressive and expensive drugs to counteract disease
progression. Such drugs may cause numerous side effects as well as
multi-drug resistance. Therefore, an effective method and apparatus
is needed that does not rely on drugs for combating infectious
organisms found in fluids.
Thus, a need exists to overcome the deficiencies of conventional
systems and methods for removing lipids from fluids such as plasma
or serum and for removing lipids from infectious organisms
contained in a fluid. Furthermore, a need exists for a medical
apparatus and method to perform delipidation rapidly, either in a
continuous or discontinuous manner of operation. A need further
exists for such an apparatus and process to perform safely and
reliably, and to produce delipidated fluid having residual plasma
solvent levels meeting acceptable standards. In addition, a need
exists for an apparatus having minimal physical connection between
a patient and the lipid apheresis process. Furthermore, a need
exists for an economical medical apparatus that is sterile and made
of a disposable construction for a single use application. Finally,
a need exists for such an apparatus and process to be automated,
thereby requiring minimal operator intervention during the course
of normal operation.
SUMMARY OF THE INVENTION
This invention is directed to systems, apparatuses and methods for
removing lipids from fluids containing lipids or from
lipid-containing organisms, or both, and more particularly, this
invention is directed to the removal of lipids from fluids
containing lipids or lipid-containing organisms using multiple
solvents. Specifically, these systems are adapted to remove lipids
from a fluid or from lipid-containing organisms, or both, by
contacting the fluid with at least two solvents in one or more
passes through a system.
In general, the systems of this invention receive a fluid that
contain lipids or that may contain lipid-containing organisms, or
both, from a fluid source, which may be a patient, a container or
other source, and contact the fluid with a first extraction solvent
provided by a first extraction solvent source. The systems also
include at least one device for contacting the fluid with a first
extraction solvent and forming a first mixture comprising the fluid
and the first extraction solvent, wherein at least a portion of the
lipids dissolve in the first extraction solvent. The systems may
include at least one first solvent removal device for contacting
the first mixture with a second extraction solvent, removing a
portion of the first mixture, and forming a second mixture
comprising the first extraction solvent, the second extraction
solvent and the fluid and at least a portion of the first
extraction solvent dissolved in the second extraction solvent. The
systems include at least one second solvent removal subsystem for
removing at least a portion of the second extraction solvent from
the second mixture. The systems may also be configured so that the
same device or combination of devices is used for removing lipids
from a fluid using a first extraction solvent and for removing the
first extraction solvent from the fluid using a second extraction
solvent.
The systems perform a method that reduces the concentration of
lipids in a fluid or removes lipids from lipid-containing
organisms. The systems are composed of three phases, referred to as
an initial phase, an intermediate phase, and a final phase. The
initial phase includes contacting a first extraction solvent with a
fluid. The first extraction solvents permeate the hollow fibers and
mix with the fluids within the lumens of the hollow fibers. The
first extraction solvent, which may be composed of many different
chemicals as defined below, causes at least a portion of the lipids
in the fluid or in the lipid-containing organisms to separate from
the fluid containing lipids or from the lipid-containing organisms.
The first extraction solvent produces a suspension of lipid
particles in the first mixture that is formed from the fluid and
the first extraction solvent. The solvent disrupts the
lipid-protein structure and frees the lipid particles, which are
not very soluble in the fluid. A product that results from the
initial phase is a first mixture composed of the fluid having at
least some lipids separated from the fluid and the first extraction
solvent, and a first extraction solvent with dissolved lipids.
The intermediate phase includes contacting the first mixture with a
second extraction solvent to remove at least a portion of the first
extraction solvent from the first mixture and may separate a
portion of lipids remaining in the partially delipidated fluid or
in the partially delipidated organisms. The intermediate phase
produces a second mixture composed of a partially delipidated fluid
and the first and second extraction solvents, and a second
extraction solvent including dissolved lipids and a portion of the
first extraction solvent. The final phase includes removing at
least a portion of the first and second extraction solvents from
the second mixture formed during the intermediate phase so that the
concentration of the solvents in the delipidated fluid will not
cause undesirable consequences in a patient receiving the
delipidated fluid.
The systems of this invention perform the initial, intermediate and
final phases to produce a fluid or lipid-containing organism having
a reduced concentration of lipids. These phases may be performed
using systems having many different configurations. For instance,
at least one embodiment of this invention uses a different
subsystem to perform each of the initial, intermediate, and final
phases of the delipidation method. Other embodiments of the
invention use a single subsystem to perform both the initial and
intermediate phases of the delipidation method and a different
subsystem to perform the final phase of the delipidation method. In
yet another embodiment, a single device is used to perform all
three phases of the delipidation method.
In certain embodiments, a first phase subsystem performs the first
phase of the delipidation method. The first phase subsystem may be
composed of numerous components, including, but not limited to, at
least one hollow fiber contactor (HFC), at least one drip through
column (DTC), at least one in-line static mixer, at least one depth
filter, a vortexer, a centrifuge, end-over-end rotation of a sealed
container, or other suitable devices, or any combination of these
devices. The intermediate phase may be performed using either the
first phase system with a second extraction solvent or an entirely
different subsystem. For instance, the intermediate phase subsystem
may be composed of at least one HFC, at least one DTC, at least one
in-line static-mixer, a depth filter, a vortexer, a centrifuge,
end-over-end rotation of a sealed container, or other suitable
device, or any combination of these devices.
The final phase of the delipidation method may be conducted using a
final phase subsystem. One embodiment of the final phase system
includes at least one HFC for removing the first and second
extraction solvents from the fluid. This may be accomplished by
passing the second mixture of partially delipdated fluid and first
and second extraction solvents through lumens of hollow fibers of
the at least one HFC while a gas, such as common air, nitrogen or
other gases; a mineral oil; or other materials, is passed through
the HFC on the shell side of the hollow fibers, or vice versa. The
final phase subsystem may consist of two or more HFCs coupled
together in a series or parallel configuration. The first and
second extraction solvents in the fluid may be reduced to a desired
level by passing the second mixture through the final phase
subsystem one or more times depending on the configuration of the
system.
An advantage of this invention is that fluids containing lipids or
lipid-containing organisms can be processed in a continuous manner
and returned to a patient without requiring withdrawal of an
unacceptable level of blood from the patient. Furthermore, this
invention may be used as a discontinuous or batch system for
processing a fluid, such as plasma from a blood bank.
Another advantage of this invention is that the concentration of
lipids or lipid-containing organisms, or both, may be reduced in a
fluid in a time efficient manner.
Yet another advantage of this invention is that portions of these
systems that contact a fluid containing lipids or lipid-containing
organisms, or both, during operation are capable of being produced
as disposable members, which reduces the amount of time needed
between patients to prepare a system for use by another
patient.
These and other features and advantages of the present invention
will become apparent after review of the following drawings and
detailed description of the disclosed embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a delipidation method of this
invention.
FIG. 2 is a schematic diagram of a first embodiment of this
invention showing an initial phase subsystem and an intermediate
phase subsystem.
FIG. 3 is a perspective view of a HFC usable to practice this
invention with a partial cut away section.
FIG. 4 is cross-sectional view of a portion of a hollow fiber
membrane of the HFC shown in FIG. 3.
FIG. 5 depicts an example of a DTC usable to practice this
invention.
FIG. 6 is a schematicized perspective view of a continuous vortexer
usable to practice this invention.
FIG. 7 is a schematicized perspective view of a batch vortexer
usable to practice this invention.
FIG. 8 is a schematicized perspective view of centrifuge usable to
practice this invention.
FIG. 9 is a schematic diagram of an embodiment of a final phase
subsystem for reducing the concentration of first and second
extraction solvents in a delipidated fluid.
FIG. 10 is a schematic diagram of another embodiment of the final
phase subsystem for reducing the concentration of first and second
extraction solvents in the delipidated fluid.
FIG. 11 is a schematic diagram of a second embodiment of this
invention showing the initial phase subsystem and the intermediate
phase subsystem.
FIG. 12 is a schematic diagram of a third embodiment of this
invention showing a single apparatus for performing the initial
phase and the intermediate phase of the delipidation method.
FIG. 13 is a schematic diagram of a fourth embodiment of this
invention showing a single apparatus for performing the initial
phase and the intermediate phase of the delipidation method.
FIG. 14 is a schematicized perspective view of the device of FIG. 2
contained in a module.
FIG. 15 is a perspective view of the device of FIG. 14 coupled to a
delipidation system.
FIG. 16 is a schematicized perspective view of the device of FIG.
11 contained in a module.
FIG. 17 is a perspective view of the device of FIG. 16 coupled to a
delipidation system.
FIG. 18 is a schematicized perspective view of the device of FIG.
12 contained in a module.
FIG. 19 is a perspective view of the device of FIG. 18 coupled to a
delipidation system.
FIG. 20 is a schematic diagram of a fifth embodiment of this
invention showing an apparatus for removing lipids from a fluid or
from a lipid-containing organism.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to systems, apparatuses and methods useful
for delipidation of fluids, including biological fluids, in
animals, including humans. These systems and apparatuses can be
used to treat arteriosclerosis and atherosclerotic vascular
diseases by removing lipids from plasma. These systems and
apparatuses can also be used to remove lipids from lipid-containing
organisms, especially infectious organisms circulating within
fluids of animals and humans.
I. Definitions and Solvents
A. Definitions
The term "fluid" is defined as fluids from animals or humans that
contain lipids, fluids from culturing tissues and cells that
contain lipids, fluids mixed with lipid-containing cells, and
fluids mixed with lipid-containing organisms. For purposes of this
invention, delipidation of fluids includes delipidation of cells
and organisms in a fluid. Fluids include, but are not limited to:
biological fluids; such as, blood, plasma, serum, lymphatic fluid,
cerebrospinal fluid, peritoneal fluid, pleural fluid, pericardial
fluid; various fluids of the reproductive system including, but not
limited to, semen, ejaculatory fluids, follicular fluid and
amniotic fluid; cell culture reagents such as, normal sera, fetal
calf serum or serum derived from any animal or human; and
immunological reagents such as, various preparations of antibodies
and cytokines from culturing tissues and cells, fluids mixed with
lipid-containing cells, and fluids containing lipid-containing
organisms, such as a saline solution containing lipid-containing
organisms.
The term "hollow fiber contactor" (HFC) is defined as being any
conventional HFC or other HFC. Typically, HFCs have an outer body,
referred to as a shell and forming a chamber, for containing a
plurality of hollow fibers positioned generally parallel to a
longitudinal axis of the shell. The hollow fibers are generally
cylindrical tubes having small diameters formed by a permeable
membrane having pores that allow certain materials pass through the
membrane. The HFC allows a first material to pass through the
lumens of the hollow fibers and a second material to pass through
the HFC on the shell side of the hollow fibers. The first material
may pass from the lumens of the hollow fibers, through the pores of
the hollow fibers and into the second material on the shell side of
the hollow fibers, or vice versa. The ability for the materials to
pass through the pores of the hollow fibers is predicated on
numerous factors, such as pore size, pressure, flow rate,
solubility, and others.
The term "drip through column" (DTC) is defined as being any
conventional DTC or other DTC. A DTC functions by forming a small
dispersion of one material and allowing the dispersed material to
fall by gravity through another material contained in the DTC.
Typically, DTCs are formed from a column that is sealed at each
end. A small orifice is positioned at one end of the DTC for
forming a small dispersion of a first material. The remainder of
the DTC is filled with a second material through which the first
material passes.
The term "lipid" is defined as any one or more of a group of fats
or fat-like substances occurring in humans or animals. The fats or
fat-like substances are characterized by their insolubility in
water and solubility in organic solvents. The term "lipid" is known
to those of ordinary skill in the art and includes, but is not
limited to, complex lipid, simple lipid, triglycerides, fatty
acids, glycerophospholipids (phospholipids), true fats such as
esters of fatty acids, glycerol, cerebrosides, waxes, and sterols
such as cholesterol and ergosterol.
The term "lipid" is also defined as including lipid-containing
organisms and lipid-containing infectious agents. Such lipids may
be found, for example, in a bacterial cell wall or viral envelope.
Lipid-containing organisms include, but are not limited to,
eukaroyotic and prokaryotic organisms, bacteria, viruses, protozoa,
mold, fungi, and other lipid-containing parasites.
The term "infectious organism" means any lipid-containing
infectious organism capable of causing infection. Some infectious
organisms include bacteria, viruses, protozoa, parasites, fungi and
mold. Some bacteria which may be treated with the method of this
invention include, but are not limited to the following:
Staphylococcus; Streptococcus, including S. pyogenes; Enterococci;
Bacillus, including Bacillus anthracis, and Lactobacillus;
Listeria; Corynebacterium diphtheriaee; Gardnerella including G.
vaginalis; Nocardia; Streptomyces; Thermoactinomyces vulgaris;
Treponema; Camplyobacter; Pseudomonas including P. aeruginosa;
Legionella; Neisseria including N. gonorrhoeae and N. meningitides;
Flavobacterium including F. meningosepticum and F. odoratum;
Brucella; Bordetella including B. pertussis and B. bronchiseptica;
Escherichia including E. coli; Klebsiella; Enterobacter; Serratia
including S. marcescens and S. liquefaciens; Edwardsiella; Proteus
including P. mirabilis and P. vulgaris; Streptobacillus;
Rickettsiaceae including R. rickettsii; Chlamydia including C.
psittaci and C. trachomatis; Mycobacterium including M.
tuberculosis, M. intracellulare, M. fortuitum, M. laprae, M. avium,
M. bovis, M. africanum, M. kansasii, M. intracellulare, and M.
lepraemurium; and Nocardia, and any other bacteria containing lipid
in their membranes.
Viral infectious organisms which may be inactivated by the above
system include, but are not limited to the lipid-containing viruses
of the following genuses: Alphavirus (alphaviruses), Rubivurus
(rubella virus), Flavivirus (Flaviviruses), Pestivirus (mucosal
disease viruses), (unnamed, hepatitis C virus), Coronavirus,
(Coronaviruses), Torovirus, (toroviruses), Arteivirus,
(arteriviruses), Paramyxovirus, (Paramyxoviruses), Rubulavirus
(rubulavriuses), Morbillivirus (morbillivuruses), Pneumovirinae
(the pneumoviruses), Pneumovirus (pneumoviruses), Vesiculovirus
(vesiculoviruses), Lyssavirus (lyssaviruses), Ephemerovirus
(ephemeroviruses), Cytorhabdovirus (plant rhabdovirus group A),
Nucleorhabdovirus (plant rhabdovirus group B), Filovirus
(filoviruses), Influenzavirus A, B (influenza A and B viruses),
Influenza virus C (influenza C virus), (unnamed, Thogoto-like
viruses), Bunyavirus (bunyaviruses), Phlebovirus (phleboviruses),
Nairovirus (nairoviruses), Hantavirus (hantaviruses), Tospovirus
(tospoviruses), Arenavirus (arenaviruses), unnamed mammalian type B
retroviruses, unnamed, mammalian and reptilian type C retroviruses,
unnamed type D retroviruses, Lentivirus (lentiviruses), Spumavirus
(spumaviruses), Orthohepadnavirus (hepadnaviruses of mammals),
Avihepadnavirus (hepadnaviruses of birds), Simplexvirus
(simplexviruses), Varicellovirus (varicelloviruses),
Betaherpesvirinae (the cytomegaloviruses), Cytomegalovirus
(cytomegaloviruses), Muromegalovirus (murine cytomegaloviruses),
Roseolovirus (human herpes virus 6), Gammaherpesvirinae (the
lymphocyte-associated herpes viruses), Lymphocryptovirus
(Epstein-Bar-like viruses), Rhadinovirus (saimiri-ateles-like
herpes viruses), Orthopoxvirus (orthopoxviruses), Parapoxvirus
(parapoxviruses), Avipoxvirus (fowlpox viruses), Capripoxvirus
(sheeppoxlike viruses), Leporipoxvirus (myxomaviruses), Suipoxvirus
(swine-pox viruses), Molluscipoxvirus (molluscum contagiosum
viruses), Yatapoxvirus (yabapox and tanapox viruses), Unnamed,
African swine fever-like viruses, Iridovirus (small iridescent
insect viruses), Ranavirus (front iridoviruses), Lymphocystivirus
(lymphocystis viruses of fish), Togaviridae, Flaviviridae,
Coronaviridae, Enabdoviridae, Filoviridae, Paramyxoviridae,
Orthomyxoviridae, Bunyaviridae, Arenaviridae, Retroviridae,
Hepadnaviridae, Herpesviridae, Poxviridae, and any other
lipid-containing virus.
These viruses include the following human and animal pathogens:
Ross River virus, fever virus, dengue viruses, Murray Valley
encephalitis virus, tick-borne encephalitis viruses (including
European and far eastern tick-borne encephalitis viruses, human
coronaviruses 229-E and OC43 and others (causing the common cold,
upper respiratory tract infection, probably pneumonia and possibly
gastroenteritis), human parainfluenza viruses 1 and 3, mumps virus,
human parainfluenza viruses 2, 4a and 4b, measles virus, human
respiratory syncytial virus, rabies virus, Marburg virus, Ebola
virus, influenza A viruses and influenza B viruses, Arenaviruss:
lymphocytic choriomeningitis (LCM) virus; Lassa virus, human
immunodeficiency viruses 1 and 2, or any other immunodeficiency
virus, hepatitis A virus, hepatitis B virus, hepatitis C virus,
Subfamily: human herpes viruses 1 and 2, herpes virus B,
Epstein-Barr virus), (smallpox) virus, cowpox virus, molluscum
contagiosum virus.
All protozoa containing lipid, especially in their plasma
membranes, are included within the scope of the present invention.
Protozoa that may be inactivated by the system and apparatus of the
present invention include, but are not limited to, the following
lipid-containing protozoa: Trypanosoma brucei, Trypanosoma
gambiense, Trypanosoma cruzi, Leishmania donovani, Leishmania
vianni, Leishmania tropica, Giardia lamblia, Giardia intestinalis,
Trichomonas vaginalis, Entamoeba histolytica, Entamoeba coli,
Entamoeba hartmanni, Naegleria species, Acanthamoeba specis,
Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae,
Plasmodium ovale, Toxoplasma gondii, Cryptosporidium parvum,
Cryptosporidium muris, Isospora belli, Cyclospora cayetansis,
Balantidium species, Babesia bovis, Babesia, microti, Babesia
divergens, Encephalitozoon intestinalis, Pleistophora species,
Nosema ocularum, Vittaforma corneae, Septata intestinalis,
Enterocytozoon, Dientamoeba fragilis, Blastocystis species,
Sarcocystis species, Pneumocystis carinii, Microsporidium
africanum, Microsporidium ceylonensis, Eimeria acervulina, Eimeria
maxima, Eimeria tenella and Neospora caninum. It is to be
understood that the present invention is not limited to the
protozoa provided in the list above.
A preferred protozoa treated with the method of the present
invention is Coccidia, which includes Isospora species,
Cryptosporidium species, Cyclospora species, Toxoplasma species,
Sarcocystis species, Neospora species, and Eimeria species. These
coccidian parasites cause intestinal disease, lymphadenopathy,
encephalitis, myocarditis, and pneumonitis.
The terms "protozoal infection" or "infectious disease" mean
diseases caused by protozoal infectious organisms. The diseases
include, but are not limited to, African sleeping sickness, Chagas'
disease, Leishmaniasis, Giardiasis, Trichomoniasis, amebiasis,
primary amebic encephalitis, granulomatous amebic encephalitis,
malaria, Toxoplasmosis, Cryptosporidiosis, Isosporiasis,
Cyclosporiasis, Balantidiasis, Babesiosis, microsporidiosis,
Dientamoeba fragilis infection, Blastocystis hominis infection,
Sarcosporidiosis, pneumonia, and coccidiosis. A preferred protozoal
infection treated with the method of the present invention is
Coccidiosis, which is caused by Isospora species, Cryptosporidium
species, Cyclospora species, Toxoplasma species, Sarcocystis
species, Neospora species, and Eimeria species. These coccidian
parasites cause human intestinal disease, lymphadenopathy,
encephalitis, myocarditis, and pneumonitis. These coccidian
parasites also cause disease in animals, including cattle, dogs,
cats, and birds. Avians, and chickens, turkeys and quail in
particular, are affected by Coccidiosis, especially by Eimeria
species such as E. acervulina, E. maxima, E. necatrix, E. bruneti,
E. mitis, E. praecox and E. tenella.
The term "continuous" refers to the process of delipidating a
fluid, such as plasma, while the animal or human remains connected
to an apparatus for delipidating the fluid. Additionally,
"continuous" refers to the internal process of the lipid removal
system, wherein the fluid continually flows within the lipid
removal system from subsystem to subsystem.
The term "batch" refers to the process of delipidating a fluid,
such as plasma, without returning or passing the delipidated fluid
directly to the animal or human during the delipidation process.
Rather, the delipidated fluid is stored. Additionally, "batch"
refers to the internal process of the lipid removal machine,
wherein the fluid does not continually flow within the lipid
removal system from subsystem to subsystem.
The term "delipidation" refers to the process of removing lipids
from a fluid or from a lipid-containing organism.
The term "first extraction solvent" is defined as one or more
solvents used in the initial stage subsystem of extracting lipids
from a fluid. The first extraction solvent enters the fluid and
remains in the fluid until removed by other subsystems. Suitable
extraction solvents include solvents that extract or dissolve
lipids, including, but not limited to, alcohols, phenols,
hydrocarbons, amines, ethers, esters, halohydrocarbons,
halocarbons, and combinations thereof. Preferred first extraction
solvents are combinations of alcohols and ethers, which include,
but are not limited to n-butanol, di-isopropyl ether (DiPE), which
is also referred to as isopropyl ether, diethyl ether (DEE), which
is also referred to as ethyl ether, sevoflourane,
perfluorocyclohexanes, trifluoroethane, isoflurane,
cyclofluorohexanol and combinations thereof.
The term "second extraction solvent" is defined as one or more
solvents that facilitate removal of at least a portion of the first
extraction solvent. Suitable second extraction solvents include any
solvent that facilitates removal of the first extraction solvent
mixed with or exposed to the fluid containing lipids or
lipid-containing organisms, or both. Second extraction solvents
include any solvent that facilitates removal of the first
extraction solvent including, but not limited to, ethers, alcohols,
phenols, hydrocarbons, amines, esters, halohydrocarbons,
halocarbons, and combinations thereof. Preferred second extraction
solvents include an ether, such as diethyl ether, which facilitates
removal of lower order alcohols, such as n-butanol, from the
fluid.
The term "patient" refers to animals and humans, which may be
either a fluid source or a recipient of delipidated fluid or
delipidated organisms.
B. Solvents
Numerous organic solvents may be used in the method of this
invention for removal of lipid from fluids and from
lipid-containing organisms, especially infectious organisms,
provided that the solvents or combinations thereof are effective in
solubilizing lipids. Suitable solvents comprise mixtures of
hydrocarbons, ethers, alcohols, phenols, esters, halohydrocarbons,
halocarbons and amines. Other solvents which may be used with this
invention include amines and mixtures of amines. Preferred solvents
are combinations of alcohols and ethers. Another preferred solvent
comprises an ether or combinations of ethers. It is preferred that
the solvent or combination of solvents has a relatively low boiling
point to facilitate removal via a combination of vacuum and
possibly heat applications.
Examples of suitable amines for use in removal of lipid from
lipid-containing organisms are those which are substantially water
immiscible. Typical amines are aliphatic amines having a carbon
chain of at least 6 carbon atoms. A non-limiting example of such an
amine is C.sub.6H.sub.13NH.sub.2. Another suitable amine is
perfluorotributyl amine.
The alcohols which are preferred for use in this invention, when
used alone, include those alcohols that are not appreciably
miscible with plasma or other fluids. Such alcohols include, but
are not limited to, straight chain and branched chain alcohols,
including pentanols, hexanols, heptanols, octanols, and alcohols
containing higher numbers of carbons. Halogenated alcohols may be
employed, including, but not limited to, heptafluoro-butanol.
When alcohols are used in combination with another solvent, for
example, an ether, a hydrocarbon, an amine, or a combination
thereof, C.sub.1 C.sub.8 containing alcohols may be used. Preferred
alcohols for use in combination with another solvent include
C.sub.4 C.sub.8 containing alcohols. Accordingly, preferred
alcohols are butanols, pentanols, hexanols, such as 1-hexanol,
heptanols, octanols, and ethanols, and iso forms thereof.
Particularly preferred are the butanols (1-butanol and 2-butanol).
As stated above, the most preferred alcohol is the C.sub.4 alcohol,
butanol. The specific choice of alcohol will depend on the second
solvent employed. In a preferred embodiment, lower alcohols are
combined with lower ethers.
Ethers, used alone, or in combination with other solvents,
preferably alcohols, are another preferred solvent for use in the
method of the present invention. Particularly preferred are the
C.sub.4 C.sub.8 containing-ethers, including but not limited to,
diethyl ether, and propyl ethers, including but not limited to
di-isopropyl ether. Asymmetrical ethers and halogenated ethers may
also be employed. Also useful in the present invention are
combinations of ethers, such as di-isopropyl ether and diethyl
ether. When ethers and alcohols are used in combination as a first
solvent for contacting the fluid containing lipids or
lipid-containing organisms, or both, any combination of alcohol and
ether may be used provided the combination is effective to
partially or completely remove lipids from the fluid or the
lipid-containing organism. In one embodiment, lipids are removed
from the viral envelope or bacterial cell wall of the infectious
organism, which reduces the infectivity of the infectious
organism.
When alcohols and ether are combined as a first extraction solvent
for removing lipids from a fluid containing lipids or
lipid-containing organisms, or both, preferred ratios of alcohol to
ether in this solvent are about 0.01% 60% alcohol to about 40%
99.99% of ether, with a preferred ratio of about 10% 50% of alcohol
with about 50% 90% of ether, with a most preferred ratio of about
20% 45% alcohol and about 55% 80% ether. An especially preferred
combination of alcohol and ether is the combination of butanol and
di-isopropyl ether. Another especially preferred combination of
alcohol and ether is the combination of butanol with diethyl
ether.
When butanol and di-isopropyl ether are combined as a first
extraction solvent for removing lipids from a fluid containing
lipids or lipid-containing organisms, or both, contained in a
fluid, preferred ratios of butanol to di-isopropyl ether in this
solvent are about 0.01% 60% butanol to about 40% 99.99% of
di-isopropyl ether, with a preferred ratio of about 10% 50% of
butanol with about 50% 90% of di-isopropyl ether, with a most
preferred ratio of about 20% 45% butanol and about 55% 80%
di-isopropyl ether. The most preferred ratio of butanol and
di-isopropyl ether is about 40% butanol and about 60% di-isopropyl
ether.
When butanol is used in combination with diethyl ether in a first
extraction solvent, preferred ratios of butanol to diethyl ether in
this combination are about 0.01% 60% butanol to about 40% 99.99%
diethyl ether, with a preferred ratio of about 10% 50% butanol with
about 50% 90% diethyl ether, with a most preferred ratio of about
20% 45% butanol and about 55% 80% diethyl ether. The most preferred
ratio of butanol and diethyl ether in a first solvent is about 40%
butanol and about 60% diethyl ether.
Hydrocarbons in their liquid form dissolve compounds of low
polarity such as the lipids in fluids and lipids found in membranes
of organisms. Hydrocarbons which are liquid at about 37.degree. C.
are effective in disrupting a lipid membrane of an infectious
organism. Accordingly, hydrocarbons comprise any substantially
water immiscible hydrocarbon which is liquid at about 37.degree. C.
Suitable hydrocarbons include, but are not limited to, the
following C.sub.5 to C.sub.20 aliphatic hydrocarbons such as
petroleum ether, hexane, heptane, and octane haloaliphatic
hydrocarbons such as chloroform, trifluoroethane,
1,1,2-trichloro-1,2,2-trifluoroethane, 1,1,1-trichloroethane,
trichloroethylene, tetrachloroethylene dichloromethane and carbon
tetrachloride; thioaliphatic hydrocarbons; perfluorocarbons, such
as perfluorocyclohexane, perfluorohexane,
perfluoromethylcyclohexane, and perfluorodimethylcyclohexane;
fluroethers such as sevoflurane; each of which may be linear,
branched or cyclic, saturated or unsaturated; aromatic hydrocarbons
such as benzene; alkylarenes such as toluene, haloarenes,
haloalkylarenes and thioarenes. Other suitable solvents may also
include: saturated or unsaturated heterocyclic compounds such as
water insoluble derivatives of pyridine and aliphatic, thio or halo
derivatives thereof; and perfluorooctyl bromide. Another suitable
solvent is perfluorodecalin.
II. Introduction
For purposes of explanation, the removal of lipids from plasma,
termed delipidation, is discussed here in detail. However, this is
not meant to limit the application of the invention solely to
delipidation of plasma. Rather, the same principles and process
apply to other fluids and to removal of lipids from
lipid-containing organisms. The delipidation system 10 of this
invention, as shown in FIG. 1, is capable of removing at least a
portion of a total concentration of lipids from a fluid containing
lipids or from lipid-containing organisms. In one embodiment,
delipidation system 10 receives fluid from a patient, or other
source, removes lipid contained in the fluid, and returns the
delipidated fluid to the patient, or other source. The delipidation
system 10 of this invention may be used as a continuous system, by
returning fluid to a patient immediately after lipids have been
removed or as a batch system, which removes lipids from a fluid but
does not return the fluids immediately to the patient. Instead, the
processed fluid can be stored and administered at a later time.
In general, the delipidation system 10 is comprised of various
combinations of subsystems that perform the initial, intermediate,
and final phases of a delipidation method. The initial phase
includes removing lipids from a fluid containing lipids or
lipid-containing organisms, or both, using a first extraction
solvent. In one embodiment, the first extraction solvent is
composed of a mixture of two solvents. The intermediate phase
includes washing the fluid received from the initial phase to
remove at least a portion of the first extraction solvent. The wash
may be conducted using at least one second extraction solvent. The
intermediate phase may also remove a portion of lipids that remain
attached to the fluid. The final phase is the removal of the first
and second extraction solvents from the fluid to an acceptable
level, such as below about 10 parts per million (ppm) or below
about 50 milligrams of solvent per 3.5 liters of fluid, for
administering the fluid to a patient without causing undesirable
consequences. Although the following paragraphs primarily describe
removal of lipids from fluids, it is understood that the same
discussion applies to removal of lipids from lipid-containing
organisms.
Each of these phases may be performed using the same device or
devices or any combination of devices. For instance, each phase may
be conducted using at least one of the following devices including,
but not limited to, an HFC, a DTC, an in-line static mixer, a depth
filter, a vortexer, a centrifuge, or end-over-end rotation of a
sealed container, or any combination of these devices. Each of
these phases may be completed using an initial phase subsystem 12,
an intermediate phase subsystem 14, and a final phase subsystem 16,
as shown schematically in FIGS. 2, 9 and 10. Each phase of the
delipidation process may be accomplished using numerous
combinations of components. The initial phase subsystem 12 removes
lipids from a fluid containing lipids or lipid-containing
organisms, or both, such as plasma, by placing a first extraction
solvent in contact with the fluid.
In the first phase subsystem 12, at least a portion of the total
concentration of lipids in the fluids is removed and, in at least
one embodiment, a substantial portion of the lipids contained in a
fluid is removed. In addition, a portion of the first extraction
solvent mixes with the fluid forming a first mixture that is sent
to the intermediate phase subsystem. This may be accomplished using
at least one of the following devices including, but not limited
to, an HFC, a DTC, an in-line static mixer, end-over-end rotation
of a sealed container, at least one depth filter, a vortexer, or a
centrifuge, or any combination of these devices.
The intermediate phase subsystem 14 receives the first mixture of
the fluid and first extraction solvent from initial phase subsystem
12 and completes the delipidation process by removing at least a
portion of the first extraction solvent and lipids from the fluid
using a second extraction solvent. During this process, a portion
of the second extraction solvent may mix with the first mixture of
fluid and first extraction solvent to form a second mixture. As
with the first phase subsystem 12, this may accomplished in many
ways. For instance, the intermediate phase subsystem 12 may be
composed of at least one of the following devices including, but
not limited to, an HFC, a DTC, an in-line static mixer,
end-over-end rotation of a sealed container, at least one depth
filter, a vortexer, or a centrifuge, or any combination of these
devices. This second mixture is then sent to the final phase
subsystem 16.
The final phase subsystem 16 receives the second mixture of fluid
and the first and second extraction solvents from intermediate
phase subsystem 14 and removes at least a portion of the residual
first extraction solvent and a majority of the second extraction
solvent from the fluid using an inert gas, such as, but not limited
to, air, nitrogen or other inert gas, or a mineral oil, or other
material. The delipidated plasma is then in a condition to be
returned to a patient or stored for administration to another
patient. The final phase subsystem 16 likewise may comprise
numerous configurations. For instance, in some embodiments, the
final phase subsystem 16 may be composed of at least one HFC. In
other embodiments, the final phase subsystem 16 may be composed of
at least two HFCs in parallel or series configuration. In certain
embodiments, the final phase subsystem 16 can remove sufficient
amounts of the first and second extraction solvents to safely
administer the fluid to a patient after the second mixture has
passed through the system only one time. In other embodiments, the
second mixture must be sent through the final phase subsystem
multiple times before the concentration of first and second
extraction solvents is reduced to an acceptable level for
administration of the delipidated fluid to the patient.
In another embodiment, each phase of the delipidation method may be
performed using a single device, such as an HFC or other such
device. For instance, each phase may be conducted using a single
HFC for conducting initial, intermediate, and final phases of the
delipidation method. The HFC may be flushed or reoriented between
each phase of the delipidation as well. In yet another embodiment,
the initial phase and the intermediate phase may be conducted using
the same device or devices that may be formed from the devices
listed immediately above or other devices. For instance, the
apparatus may include, but is not limited to, an in-line static
mixer, a vortexer, or a HFC, or any combination thereof.
This process is shown schematically in FIG. 1 as being adapted to
remove lipids from plasma or from lipid-containing organisms, or
both. For instance, whole blood is drawn from a patient using
conventional procedures and is subjected to a conventional plasma
separation process using, for instance, cellular separation systems
that may be composed of, but are not limited to, apheresis and
plasmapheresis systems, such as SPECTRA and TRIMA manufactured by
Cobe BCT, Gambro BCT, Lakewood, Colo.; AUTOPHERESIS-C manufactured
by Baxter Healthcare Corporation, Deerfield, Ill.; or AS104
manufactured by Fresenius, Berlin, Germany. In another embodiment,
blood is combined with an anticoagulant, such as sodium citrate,
and centrifuged at forces approximately equal to 2,000 times
gravity. The red blood cells are then aspirated from the plasma.
The plasma separation process collects plasma and returns the blood
cells to the patient. The plasma is then subjected to the lipid
removal process of this invention, which is described in detail
below.
III. The Delipidation System
As discussed above, the delipidation system 10 may be composed of
numerous designs. In one embodiment, delipidation system 10 is
composed of at least three subsystems. These subsystems may be
composed of numerous components to accomplish the objectives
described above. In another embodiment, a single system may be used
to perform two or more phases of the delipidation method. Set forth
below are numerous embodiments formed from different components
that are capable of achieving these objectives. These embodiments
are described to teach the invention and are not meant to limit the
scope of the invention. Rather, each embodiment is but one of many
possible configurations that can be used to accomplish the
objectives described above.
Suitable materials for use in any of the apparatus components as
described herein include materials that are biocompatible, approved
for medical applications that involve contact with internal body
fluids, and in compliance with U.S. PV1 or ISO 10993 standards.
Further, the materials should not substantially degrade, from, for
instance, exposure to the solvents used in the present invention,
during at least a single use. The materials should typically be
sterilizable either by radiation or ethylene oxide (EtO)
sterilization. Such suitable materials should be capable of being
formed into objects using conventional processes, such as, but not
limited to, extrusion, injection molding and others. Materials
meeting these requirements include, but are not limited to, nylon,
polypropylene, polycarbonate, acrylic, polysulphone, polyvinylidene
fluoride (PVDF), fluoroelastomers such as VITON, available from
DuPont Dow Elastomers L. L. C., thermoplastic elastomers such as
SANTOPRENE, available from Monsanto, polyurethane, polyvinyl
chloride (PVC), polytetrafluoroethylene (PTFE), polyphenylene ether
(PFE), perfluoroalkoxy copolymer (PFA), which is available as
TEFLON PFA from E.I. du Pont de Nemours and Company, and
combinations thereof.
The valves used in each embodiment may be, but are not limited to,
pinch, globe, ball, gate or other conventional valves. Thus, the
invention is not limited to a valve having a particular style.
Further, the components of each system described below may be
coupled directly together or coupled together using conduits that
may be composed of flexible or rigid pipe, tubing or other such
devices known to those of ordinary skill in the art.
A. First Embodiment 1. Initial Phase Subsystem
FIG. 2 shows a delipidation system 10 composed of an initial phase
subsystem 12 and an intermediate phase subsystem 14, and FIGS. 9
and 10 show two embodiments of a final phase subsystem 16.
Referring to FIG. 2, initial phase subsystem 12 is formed with a
HFC 18. While the embodiment depicted in FIG. 2, shows a single
HFC, the initial phase subsystem 12 is not limited to a single HFC
but may include additional HFCs. The number of HFCs used in each
subsystem may be dictated by the amount of lipid removal desired.
The number and size of the HFCs are a function of the flow rate of
fluids or gases within,the lumens of the hollow fibers and on the
shell side of the hollow fibers of the HFC, the porosity of the
hollow fibers, and the amount of surface area of the hollow fiber
membrane. Adjusting one of these factors requires the other factors
be changed in order to yield the same output at the same rate.
Additionally, patients having higher initial levels of lipids may
require more HFCs to be used to obtain the desired degree of lipid
removal.
HFC 18, as shown in more detail in FIG. 3, may be formed from a
generally hollow cylindrical body having a diameter ranging between
about 11/2 inches to about 4 inches that forms a chamber 22
containing a plurality of hollow fibers 20. Hollow fibers 20 are
tubes having small diameters, such as between about 0.2 mm and
about 1.0 mm, and typically number between about 3,000 and about
5,000. However, hollow fibers 20 may number one or more. Chamber 22
is formed by the inside surface of the cylindrical body of HFC 18
and the outside surfaces of hollow fibers 20. Chamber 22 is
commonly referred to as the shell side of the hollow fibers 20.
Each hollow fiber 20, as shown in FIG. 4, is a cylindrical tube
having a small diameter and is formed from a membrane having pores
26 sized to allow gases and liquids to pass through the membrane.
Pores 26 may have a diameter within the range of between about 5
kilodaltons and about 500 kilodaltons or between about 3 nanometers
and about 300 nanometers. Varying the size of pores 26 can allow
either more or less materials to pass through pores 26. Hollow
fibers 20 are positioned in HFC 18 so that their longitudinal axes
are generally parallel to the longitudinal axis of the HFC 18.
Pores 26 need only be large enough to allow the first and second
extraction solvents and a gas to diffuse through pores 26 and for
lipids to diffuse through pores 26 and into the solvents.
While not being bound by the following statements, the following
discussion is a possible explanation of the operation of the system
at the pores 26 of the hollow fibers. The hollow fibers 20 may be
formed of either hydrophobic or hydrophilic materials. If hollow
fibers 20 formed from a hydrophobic material are used, the solvent
fills pores 26 and an interface forms between the solvent in pores
26 and the fluid that remains in the lumens. The solvent diffuses
across the interface into the fluid, but there is minimal mixing of
the fluid and the solvent. Thus, there exists very little
possibility of an emulsion forming. The lipids that may have been
solubilized by the action of the solvents diffuse into the solvent
in the pores 26 at the interface. The lipids continue to diffuse
through pores 26 until the lipids are swept away by the solvent
flowing through HFC 18 on the shell side 22 of the lumens. If a
hydrophilic material is used to form hollow fibers 20, pores 26
fill with fluid, and the solvent does not fill pores 26. The lipids
then diffuse through pores 26.
The preferred material is a hydrophobic material because the
highest transport rate is achieved when pores 26 are filled with
the material having the highest solubility for the material desired
to be passed through pores 26. In this case, lipids are more
soluble in the solvents described above than in the fluid.
The flow rate of the fluid and first extraction solvent through HFC
18 dictates the required amount of permeable surface area on hollow
fibers 20. For instance, the slower the flow rate, the smaller the
surface area required, and, conversely, the faster the flow rate,
the larger the surface area required. This is dictated by a mass
transport formula. The formula below illustrates the situation for
a soluble gas:
.function..times..times..times..DELTA..times..times..times..times..times.-
.times..times. ##EQU00001## where C.sub.out represents the liquid
phase concentration (output), C.sub.in represent the liquid phase
concentration (input), K.sub.l represents the overall mass
transport coefficient, A.sub.m represents the total membrane
contact area, Q.sub.l represents the liquid flow rate, H represents
the Henry's Law coefficient and P represents the gas phase partial
pressure. If P.sub.in and P.sub.out are small in magnitude and/or H
is large, the terms P and H are negligible and the first equation
simplifies to:
.times..function..times. ##EQU00002## Examples of commercially
available HFCs are the CELGARD mini model no. G471, G476, or G478,
available from CelGard, Charlotte, N.C., and the Spectrum MINIKROS
model no. M21S-600-01N, available from Spectrum Laboratories, Inc.,
Rancho Dominguez, Calif.
Initial phase subsystem 12 is configured to allow a fluid
containing lipids or lipid-containing organisms, or both, to flow
through lumens of hollow fibers 20 of HFC 18 and to allow a first
extraction solvent to flow through chamber 22 on the shell side of
HFC 18, or vice versa. In one embodiment, the fluid flows through
the lumens of hollow fibers 20 in the same general direction as the
first extraction solvent. However, in another embodiment, the fluid
flows generally opposite to the direction of flow of the first
extraction solvent in the shell side 22, referred to as
countercurrent flow. Pores 26 of hollow fibers 20 allow the first
extraction solvent to cross the hollow fiber membrane 20 and to
contact the fluid. The first extraction solvent separates the
lipids contained in the fluids. If the fluid is a plasma taken from
blood, the first extraction solvent separates the lipids from the
proteins in the plasma. At least a portion of the separated lipids
diffuse through pores 26 into the shell side 22 of hollow fibers 20
of HFC 18 and are deposited into waste receptacle 40. In certain
embodiments, a portion of the separated lipids do not diffuse
through pores 26 but attach to the inside surface of the hollow
fiber membrane 20. Thus, initial phase subsystem 12 separates at
least a portion of the lipids contained in the fluid and in certain
embodiments separates a significant amount of the lipids. While a
portion of the first extraction solvent returns to the shell side
22 of the HFC across hollow fiber membrane 20, a portion of the
first extraction solvent remains mixed with the fluid in the lumens
of hollow fibers 20 forming a first mixture.
A fluid containing lipids or lipid-containing organisms, or both,
is supplied to HFC 18 from a fluid source 28, which may be a
container, an apheresis system, such as any one of the previously
mentioned systems, or other source. The fluid may be administered
to the lumens of hollow fibers 20 of HFC 18 using gravity, a
vacuum, a pump 30, or other means. Pump 30 may be a peristaltic
pump, such as MASTERFLEX L/S model number 07523-40 available from
Cole Parmer Instrument Company, Vernon Hills, Ill., or other pumps
not having vanes that contact the fluid being pumped.
The shell side 22 of HFC 18 is coupled to a first extraction
solvent source 32, which supplies a first extraction solvent to HFC
18. First extraction solvent source 32 includes vent 34 for
relieving pressure and preventing unsafe conditions. The first
extraction solvent may be administered to shell side 22 of the HFC
18 using gravity, a vacuum, a pump 36, which may be a peristaltic
pump or other pump, or other means. HFC 18 includes a waste port 38
on the shell side 22 of HFC 18 for removing the first extraction
solvent. The waste port 38 is in fluid communication with a waste
receptacle 40, which may be a container or other device for
containing the first extraction solvent. A valve 42 may be coupled
between waste port 38 and waste receptacle 40 for controlling the
discharge of the first extraction solvent from the shell side 22 of
HFC 18. The lumens of hollow fibers 20 of HFC 18 are coupled to the
intermediate phase subsystem 14. 2. Intermediate Phase
Subsystem
The intermediate phase subsystem 14 is composed of at least one DTC
and may be composed of two DTCs 44 and 46 in series, as shown in
FIG. 2, or in parallel (not shown). The input port of DTC 44 is in
fluid communication with the lumens of hollow fibers 20 of HFC 18
and receives the first mixture from HFC 18. A DTC, such as DTC 44
and 46, is typically composed of a hollow cylindrical tube or
column 48 having a cap 50 and 52 at each end, as shown in FIG. 5.
The DTC includes an injection device 54, which is typically a small
gauge needle, for injecting a fine dispersion of the first mixture
into the hollow cylinder forming the DTC. The dispersed first
mixture falls by gravity through the second extraction solvent. As
the first mixture falls through the second extraction solvent, the
second extraction solvent separates a portion of the first
extraction solvent from the fluid. For instance, in one embodiment,
the first extraction solvent is a mixture of n-butanol and DiPE,
and the second extraction solvent is DiPE. The second extraction
solvent removes a portion of the n-butanol and may remove a
substantial amount of the n-butanol. The second extraction solvent
may also separate lipids remaining in the fluid. The lipids
extracted from the first mixture are dissolved in the second
extraction solvent, and the fluid eventually comes to rest on cap
50 of DTC 44. At this point, the fluid is composed of a mixture of
the first and second extraction solvents and is referred to as a
second mixture.
DTCs 44 and 46 are in fluid communication with a second extraction
solvent container 56, which contains the second extraction solvent,
as shown in FIG. 2. The second extraction solvent can flow from the
second extraction solvent container 56 to DTCs 44 and 46 by
gravity, by pump 58, which may be a peristaltic pump or other pump,
or by other means. A three-way valve 60 controls the flow of the
second extraction solvent into DTC 44. Vents 62 and 64 are coupled
to DTCs 44 and 46, respectively, and for safe operation and are
controlled using valves 66 and 68. Valve 70 controls the flow of
the second mixture, composed of the fluid and first and second
extraction solvents, between DTC 44 and DTC 46. Valves 80 and 82
control the flow of the second mixture from DTC 46 to the remainder
of intermediate phase subsystem 14.
The intermediate phase subsystem 14 may also include a vortexer 72
for mixing the first and second extraction solvents with the fluid.
Vortexer 72 may be composed of many designs, such as a continuous
vortexer shown in FIG. 6 or a batch vortexer shown in FIG. 7.
Vortexer 72 also includes a vent 84 for safe operation. Referring
to FIG. 6, a continuous vortexer is generally composed of a
cylindrical tube configured in a spiral formation. This
configuration creates vortices within a fluid flowing through the
cylindrical tube and is capable of processing the fluid in a
continuous fashion as the fluid flows through vortexer 72. The
vortexer 72 is operated using external vibration. An alternative
design is a batch vortexer 72, as shown in FIG. 7. The batch
vortexer 72 is composed of housing 74 that contains a plurality of
vortex chambers 76. The batch vortexer 72 is capable of receiving a
fluid and a solvent through inlet port 78. The batch vortexer 72 is
externally vibrated to create vortices within each vortex chamber
76. The non-rotating vortexer 72 is advantageous because of its
simple design is less expensive than more complicated designs.
Thus, it may be used more efficiently than other devices in a
disposable system. Further, vortexer 72 does not contain any
bushings, bearings or moving parts that are subject to failure.
Intermediate phase subsystem 14 may also include a centrifuge 86,
as shown in FIG. 2 and in more detail in FIG. 8. Centrifuge 86 may
be configured as a discontinuous flow-through channel in the shape
of a ring that is spun about its axis. Functionally, the second
mixture of the fluid and the first and second extraction solvents
flow into the centrifuge ring through one port and exit centrifuge
86 as separated fluid and first and second extraction solvents. The
second mixture may be sent to centrifuge 86 using gravity, a pump
88, such as a peristaltic pump or other type of pump, vacuum, or
other means. The spinning action of centrifuge 86 generates
centrifugal forces that separate the constituents of the second
mixture. The mixture of the fluid having a small amount of first
and second extraction solvent is sent to the final phase subsystem
16 through valve 90. The first and second extraction solvents that
are separated from the fluid in centrifuge 86 are sent through
valve 92 to either waste receptacle 40 or to a condenser 94.
Condenser 94 is included in intermediate phase subsystem 14 if DEE
is used as a first or second extraction solvent, and may be used
with other solvents.
The initial phase subsystem 12 and intermediate phase subsystem 14
include various sensors 96 located throughout the system for
monitoring pressure, temperatures, flow rates, solvent levels and
other parameters. The sensors may be any conventional sensor for
the parameter being measured. 3. Final Phase Subsystem
The final phase subsystem 16 removes at least a portion of the
first extraction solvent and the second extraction solvent from the
fluid that was not removed in the intermediate phase subsystem 14.
The final phase subsystem 16 may be composed of at least two
embodiments, as shown in FIGS. 9 and 10. Specifically, FIG. 9 shows
a once-through system that is capable of removing at least a
portion of the first and second extraction solvents from a fluid by
passing the second mixture through the system only one time so that
the concentrations of these solvents are less than a particular
threshold, which may be about 10 ppm, thereby enabling the fluid to
be administered to a patient without undesirable consequences. FIG.
10 depicts a recirculating subsystem that is also capable of
reducing the concentration of the first and second extraction
solvents to a level beneath a particular threshold. However,
solvent concentrations are reduced to adequate levels by passing
the second mixture through the subsystems one or more times. Each
of these embodiments is discussed in more detail below. (a)
Once-Through Solvent Removal Subsystem
The once-through subsystem 99 depicted in FIG. 9 is composed of two
HFCs 100 and 102 for removing the first and second extraction
solvents from the fluid. However, the once-through subsystem may be
composed of any number of HFCs depending on the effective surface
area of the hollow fibers as calculated using the methodology and
formulas previously described. The once-through subsystem includes
a pervaporation buffer container 104 for receiving the fluid from
intermediate phase subsystem 16. The pervaporation buffer container
104 is coupled to a container 106, which may be, but is not limited
to, an air bag for containing the air that escapes from buffer
container 104. The fluid may flow into HFC 100 by gravity, pump
108, which may be a peristaltic pump or other pump not having vanes
that contact the fluid being pumped, or other means.
Pervaporation buffer container 104 is coupled to the lumens of
hollow fibers 110 of HFC 100 so that a fluid may flow through the
lumens of hollow fibers 110 during operation. The lumens of hollow
fibers 110 of HFC 100 are in fluid communication with the lumens of
hollow fibers 112 of HFC 102. A chamber 114, also referred to as
the shell side of hollow fibers 112 of HFC 102 is capable of
receiving a gas, such as air, nitrogen, or other material, such as
mineral oil or the like. However, in another embodiment, the gas is
sent through the lumens of hollow fibers 112 and the fluid is sent
through HFC 102 on the shell side of hollow fibers 112. Chamber 114
of HFC 102 is coupled to a solvent removal system 116 and is in
fluid communication with chamber 118 of HFC 100. Solvent removal
system 116 cycles a material in a gaseous state through chambers
114 and 118 to remove the first and second extraction solvents from
the fluid contained within lumens of hollow fibers 110 and 112. In
certain embodiments, the gaseous material is common air, nitrogen,
or other inert gas. Solvent removal system 116 may also cycle a
mineral oil or other material through chambers 114 and 118.
Solvent removal system 116 includes a carbon bed 120, a first
sterile filter 122, a pump 124, and a second sterile filter 126.
These elements may be coupled together using a conduit, a coupling
or other connection device. Carbon bed 120 is coupled to HFCs 100
and 102 for receiving gases having first and second extraction
solvents. Carbon bed 120 removes most of the first and second
extraction solvents from the gases being passed through the
chambers 114 and 118 of HFCs 100 and 102. First sterile filter 122
and second sterile filter 126 are sterile barriers allowing the
system to be partially disassembled without contaminating the
entire system. Suitable filters may have a lipophilic or
hydrophilic membranes. In another embodiment, the solvent removal
system 116 may be composed of one or more filters, condensers or
cold traps, or catalytic combustors to remove the solvent vapors
from the gas before it is recycled through HFCs 100 and 102.
Final phase subsystem 16 also includes an output buffer container
128 for collecting the delipidated fluid after passing through the
lumens of hollow fibers 110 and 112 of HFCs 100 and 102. Output
buffer container 128 may be any container that is preferably
sterile and capable of holding the delipidated fluid. A scale 130
may be included to determine the amount of fluid present in output
buffer container 128 and for other analytical purposes.
Final phase subsystem 16 may also include at least one sensor 132
for sensing the presence of a solvent in the fluid leaving final
phase subsystem 16. Various types of solvent sensors may be used as
sensor 132. Preferably, the sensors are capable of detecting very
low levels of solvent. One such sensor is capable of measuring
differences in infrared absorption spectra between solvents and
plasma. Using approaches known to those skilled in the art, several
light sources and detectors can be integrated into a non-contact
optical sensor that can be calibrated to measure the concentrations
of one or all of the solvents. Another useful sensor includes a
resistive sensor that uses a resistance processor to detect the
presence of very low levels of solid particles, such as model
number TGS2620 or TGS822 available from Figaro USA Inc., Glenview,
Ill. Yet another type of optical sensor includes one that
determines or identifies molecules comprising a solvent.
Optionally, indirect measurement of solvent level in the fluid
could be performed by measuring the amount of solvent in solvent
removal system 116. However, direct measurement is more reliable,
because an obstruction in filter(s) 122 or 126, or other flow
impediment may falsely indicate that solvent has been extracted,
when the solvent has in fact remained in the fluid.
HFCs 100 and 102 have been tested and successfully reduce total
concentrations of solvents, such as di-isopropyl ether and di-ethyl
ether, in water and plasmas, such as human and bovine plasma, using
different HFCs, pressures, and flow rates, as shown in Table 1
below. Table 2 below shows the reduction in concentrations of DiPE
in water, bovine plasma and human plasma as a function of time.
HFCs 100 and 102 may have a total surface area of permeable
membrane formed by the hollow fibers between about 4,200 square
centimeters and about 18,000 square centimeters, depending on the
type of HFC used. Further, the gas flow rate was varied between
about 2 liters per minute to about 10 liters per minute, and the
plasma flow rate was varied between about 10 mL per minute to about
60 mL per minute. Operating the once-through final subsystem 99 in
this manner can reduce the initial concentrations of solvents from
between about 28,000 ppm and 9,000 ppm to between about 1327 ppm
and about 0.99 ppm within between about 14 minutes and 30
minutes.
TABLE-US-00001 TABLE 1 Initial Lumen Pressure Pressure Volume DIPE
Final Module Flow rate Air Flow before HFC after HFC Carbon Treated
conc DIPE (Quantity) Orientation Phase (cc/min) (L/min) (psig)
(psig) (g) (L) ppm co- nc ppm Effect of Module Fresenius F6 (1)
Horiz H.sub.2O 20 9.3 0.44 -0.74 100 0.75 9045 1327 & F8 (1)
Spectrum Horiz H.sub.2O 20 ~9 -0.13 -1.01 100 0.75 9684 3 11200
cm.sup.2 (2) Celgard (1) Vertical H.sub.2O 20 11 -0.2 -1.21 100 0.5
10518 0.99 Spectrum Horiz Human 20 9.2 0.91 -0.06 100 0.75 12200 6
11200 cm.sup.2 (2) Plasma Celgard (2) Vertical Human 20 10.1 -0.16
-1.3 150 0.25 27822 9 Spectrum Horiz H.sub.2O 18 0.71 -0.83 0.75
9055 18 11200 cm.sup.2 (2) Spectrum Horiz H.sub.2O 20 0.65 -0.88
0.75 8851 22 11200 cm.sup.2 (2) Spectrum Horiz H.sub.2O 40 0.7
-0.85 0.75 10016 11 11200 cm.sup.2 (2) Spectrum Horiz H.sub.2O 60
0.65 -0.82 100 0.75 10134 93 11200 cm.sup.2 (2) Celgard (1)
Vertical H.sub.2O 20 9.3 0.44 -0.2 100 0.75 7362 22 Celgard (1)
Vertical H.sub.2O 40 9.2 0.44 -0.2 100 0.75 9366 193 Effects of
Pressure Celgard (2) Vertical Human 20 9.7 0.11 -1.33 100 0.25
18782 ND Celgard (2) Vertical Human 20 9.2 -1.39 -2.93 100 0.25
15246 ND Celgard (2) Vertical Human 20 8.1 -2.79 -4.12 100 0.25
13144 ND Full Body Volume Celgard (2) Vertical Human 20 5.3 -1.1
-1.8 300 3100 9040 24
TABLE-US-00002 TABLE 2 DIPE concentrations [ppm] Time [min] Water
Bovine Human (Norm) 0 6782.094027 9473.974574 11351.10738 2
1716.182938 3012.065643 3868.491245 4 118.591244 485.1426701
636.1926821 6 16.36572648 102.9572692 125.8618995 8 5.364620368
36.33996072 60.440048 10 4.230662874 16.08489373 34.50180421 12
2.019251402 23.54890574 16.71332069 14 1.537721419 9.218693213
17.32898791 16 3.169227108 6.549024255 15.26858655
Various control devices are included in final phase subsystem 16.
For instance, the once-through subsystem includes a fluid level
sensor 134 and a temperature sensor 136 coupled to pervaporation
buffer container 104, a fluid level sensor 138, a fluid presence
detector 140, an encoder 142 and a current overload detector 144
for controlling pump 108, and a pressure sensor 146. Solvent
removal system 116 includes a fluid presence detector 148, a
temperature sensor 150, a current overload detector 152 for
controlling pump 124, and pressure sensors 154 and 156. (b)
Recirculating Solvent Removal Subsystem
The recirculating solvent removal subsystem 218 is configured much
like the once-through subsystem. FIG. 10 depicts the recirculating
system as including two HFCs 160 and 162 for removing the first and
second extraction solvents from the fluid. While the embodiment
depicted in FIG. 10 includes two HFCs positioned in parallel, the
subsystem may be composed of any number of HFCs positioned in
parallel, series, or other configuration. In another embodiment,
the subsystem may be composed of only a single HFC.
HFCs 160 and 162 are preferably sized according to the calculations
and methodology set forth above. HFCs 160 and 162 contain hollow
fibers 164 and 166, respectively, for receiving the fluid mixed
with residual first and second extraction solvents, referred to as
the second mixture, from intermediate phase subsystem 14. The
biological flows from intermediate phase subsystem 14 to a
recirculation vessel 168. Recirculation vessel 168 receives the
fluid mixture from the intermediate phase subsystem 14 and from
HFCs 160 and 162. The mixture of fluid and remaining first and
second extraction solvents not removed in intermediate phase
subsystem 14 is sent to HFCs 160 and 162 using gravity flow, a pump
170, which may be a peristaltic pump or other pump not having vanes
that contact the fluid being pumped, vacuum, or other means. The
second mixture flows through the lumens of hollow fibers 164 and
166 of HFCs 160 and 162 while a gaseous material, such as common
air or nitrogen or other inert gas, or other material is passed
through chambers 172 and 174 of HFCs 160 and 162, respectively, or
vice versa. Chambers 172 and 174 are also referred to as the shell
sides of HFCs 160 and 162. The second mixture is circulated between
recirculation vessel 168 and HFCs 160 and 162 until a sensor 176
detects that the concentration of the first and second extraction
solvents in the fluid is less than a predetermined threshold, such
as less than about 10 ppm or below about 50 milligrams of solvent
per 3.5 liters of fluid, for allowing the fluid to be administered
to a patient without undesirable consequences. The fluid is then
sent to output buffer 210 by closing valve 212 and opening valve
214. The amount of fluid present in output buffer 210 may be
determined using scale 216.
The recirculating subsystem 218 also includes a number of control
devices. For instance, the recirculating subsystem 218 includes
fluid level sensors 196 and 198, a fluid presence detector 200, a
current overload detector 202 and an encoder 204 for controlling
pump 170, a pressure sensor 206, and a temperature sensor 208.
These sensing devices are used for controlling the system 218.
A solvent removal system 178 is included within the recirculating
subsystem 218 for removing the first and second extraction solvents
from the gas. Solvent removal subsystem 178 routes the gas through
recirculation vessel 168 to allow more solvent from the fluid
contained in vessel 168 to be removed. Solvent removal subsystem
178 includes a carbon bed 180 for removing solvents from the air, a
first sterile filter 182 and a second sterile filter 184 for
allowing the solvent removal system 178 to be partially
disassembled without contaminating the entire system. Suitable
filters may have a lipophilic or hydrophilic membranes. In an
alternative embodiment, solvent removal subsystem 178 may be
composed of one or more filters, condensers or cold traps, or
catalytic combustors to remove the solvent vapors from the gas
before it is recycled through HFCs 160 and 162. A pump 186 may be
provided for circulating the gas through the subsystem. Solvent
removal subsystem 178 may also include a temperature sensor 188,
pressure sensors 190 and 192, and a current overload sensor 194 for
controlling pump 186.
HFCs 160 and 162 have been tested and successfully reduce total
concentrations of solvents, such as di-isopropyl ether and di-ethyl
ether, in water and plasmas, such as human and bovine plasma, as
shown in Table 3 below. HFCs 160 and 162 may have a total surface
area of permeable membrane formed by the hollow fibers between
about 4,200 square centimeters and about 18,000 square centimeters,
depending on the type of HFC used. Further, the gas flow rate was
varied between about 2 liters per minute to about 14 liters per
minute, and the plasma flow rate was varied between about 9 mL per
minute to about 900 mL per minute. Operating the recirculating
subsystem 218 in this manner can reduce the initial concentrations
of solvents, such as DiPE and DEE, from between about 31,000 ppm
and 9,400 ppm to between about 312 ppm and about 2 ppm within
between about 14 minutes and 80 minutes.
TABLE-US-00003 TABLE 3 Solvent Initial Final Time Lumen to be Shell
Lumen Module Solvent Solvent re- Material Removed Material Shell
Flow Flow (Surface Area) Conc (ppm) Conc (ppm) circulating Water
Diethyl Air 7 L/min 220 Fresenius 31000 265 30 min Ether F80A
(18000 cm2) Water Diisopropyl Air 12.3 L/min 750 Celgard 6782 2 14
min Ether (8400 cm2) Bovine Diisopropyl Air 12.3 L/min 750 Celgard
9473 7 16 min Plasma Ether (8400 cm2) Human Diisopropyl Air 12.3
L/min 750 Celgard 11351 15 16 min Plasma Ether (8400 cm2) Water
Diisopropyl Heavy 10 cc/min 4 cc/min Spectrum 4635 312 80 min Ether
Mineral Oil (8000 cm2)
4. Example of Use
As described above, the delipidation device depicted schematically
in FIG. 2 is capable of removing at least a portion of a total
concentration of lipids or lipid-containing organisms from a fluid.
In this particular example, the fluid used was a bovine plasma. The
bovine plasma was first introduced into the lumens of hollow fibers
20 of HFC 18 at a flow rate of 50 mL/min and contacted with a first
extraction solvent located in chamber 22 of HFC 18, which is the
shell side of hollow fibers 20. The first extraction solvent was
composed of a mixture of about 60 percent di-isopropyl ether (DiPE)
and about 40 percent n-butanol and was sent through HFC 18 at a
flow rate of 200 mL/min. As described above, this produced a first
mixture of plasma and first extraction solvent in the lumens of
hollow fibers 20. The first mixture was then washed with a second
extraction solvent, which was composed of diethyl ether (DEE), in
DTCs 44 and 46, which were about 20 inches long and about 0.375
inches in diameter and positioned in series. Sending the first
mixture through DTCs 44 and 46 reduced the concentration of lipids
in the fluid or lipid-containing organisms, or both, and formed a
second mixture composed of plasma and the first and second
extraction solvents. The resulting plasma from the final DTC wash
was circulated through vortexer 72 and centrifuge 81 for about 6
sequential washes. Vortexer 72 had a capacity of 500 mL, and
centrifuge 81 had a capacity of 80 mL. Further, centrifuge 81 had a
relative centrifugal force (RCF) of 560 times gravity
(506.times.g).
The second mixture was then introduced into a final phase subsystem
218 as shown in FIG. 10. The second mixture was circulated through
HFCs 160 and 162 at a flow rate of about 750 mL/min, wherein each
HFC had a holdup volume of about 50 mL and an area of about 4200
cm.sup.2. Air was circulated through the shell side of hollow
fibers 164 and 166 of HFCs 160 and 162 to extract the residual
first and second extraction solvents from the fluid. Carbon bed 180
was used to remove solvent vapors in the recirculating gas stream.
This process was continued until the solvent vapor detector 176
indicated that solvent levels were below a particular threshold,
such as below 10 ppm or below about 50 milligrams of solvent per
3.5 liters of fluid, enabling the remaining solvent to be removed
with a final pass through the carbon bed 180. Upon indication that
sufficient levels of solvent were removed, the fluid was then
tested to determine the effectiveness of the apparatus.
The process resulted in a reduction of cholesterol of about 90
percent, which was measured by standard lipid profile enzymatic
assays that are known in the art. For a volume of approximately 300
mL of plasma and using discontinuous subsystems emulating the
system described above, the delipidation process described above
takes approximately 20 minutes, thereby achieving a delipidation
throughput of about 15 mL/min.
B. Second Embodiment
1. Initial Phase Subsystem
FIG. 11 depicts an initial phase subsystem 12 composed of a DTC 220
for contacting a first extraction solvent with a fluid containing
lipids or lipid-containing organisms, or both, and for removing at
least a portion of the total concentration of lipids from the
fluid. While FIG. 11 shows a single DTC, initial phase subsystem 12
may be composed of one or more DTCs coupled in series or parallel
or any combination thereof. DTC 220 may be configured as shown in
FIG. 5.
DTC 220 is in fluid communication with a fluid source 222 for
receiving a fluid. Fluid source 222 may be positioned to feed the
fluid to DTC 220 using gravity flow, a vacuum, a pump 224, which
may be a peristaltic pump or other pump not having vanes that
contact the fluid being pumped, or other means. DTC 220 contains a
first extraction solvent supplied by first extraction solvent
source 226 via gravity, a vacuum, pump 228, which may be a
peristaltic pump, centrifugal pump or other suitable pump, or other
suitable means. First extraction solvent source 226 includes a vent
227 for safe operation. As described above, DTC 220 contains a
dispersion device, which is typically a small gauge needle for
inserting the fluid into DTC 220 as a fine dispersion. At least a
portion of the lipids contained within the fluids separate and
dissolve in the first extraction solvent. This mixture of solvent
and dissolved lipids in DTC 220 are transferred through valve 230
to waste receptacle 232, which includes a vent 234 for safe
operation. The fluid that is placed into DTC 220 falls through the
first extraction solvent and comes to rest in the bottom portion of
DTC 220. The fluid is then taken from DTC 220 and sent to
intermediate phase subsystem 14 as a first mixture of fluid and
first extraction solvent. 2. Intermediate Phase Subsystem
Intermediate phase subsystem 14 shown in FIG. 11 includes eight
DTCs 236 250 for removing at least a portion of the lipids
contained within the fluid that were not removed within initial
phase subsystem 12. While FIG. 11 shows eight DTCs, intermediate
phase subsystem 14 may be composed on any number of appropriately
sized DTCs, such as one or more. Further, the DTCs may be
configured in series, as shown in FIG. 1, or in parallel, or in any
combination thereof. DTC 236 receives a first mixture of the fluid
and the first extraction solvent from DTC 220 of initial phase
subsystem 12. Each DTC 236 250 is filled with a second extraction
solvent received from second extraction solvent source 252. Second
extraction solvent source 252 also includes a vent 254 for safe
operation.
The first mixture of fluid containing lipids or lipid-containing
organisms, or both, and first extraction solvent is sent through
each of DTCs 236 250. During operation of intermediate phase
subsystem 14, at least a portion of the first extraction solvent
that mixed with the fluid in initial phase subsystem 12. Further,
the second extraction solvent may remove a portion of the lipids
that may not have been separated from the fluid by initial phase
subsystem 12. Also, a portion of the second extraction solvent may
mix with the mixture of fluid and first extraction solvent to form
a second mixture. This second mixture of fluid and first and second
extraction solvents is then sent to final subsystem 16 through
valve 256. The waste second extraction solvent may include lipids
and first extraction solvent removed from the fluid. The waste
extraction solvent is removed from DTCs 236 250 using gravity, a
vacuum, pump 262, or other means and may either be sent through
condenser 258 or to waste receptacle 232 using valve 260. Pump 262
may be either a peristaltic pump or other type pump. 3. Final Phase
Subsystem
The embodiment of the delipidation system 10 shown in FIG. 11 may
be used with either the once-through subsystem 99 shown in FIG. 9
or the recirculating subsystem 218 shown in FIG. 10. However, this
embodiment of delipidation system 10 is not limited to being used
with these embodiments of final phase subsystem 16. Rather, this
embodiment of delipidation system 10 shown in FIG. 11 may be used
with any system capable of reducing the concentrations of first and
second extraction solvents in the fluid to a level beneath a
particular threshold enabling the fluid to be administered to a
patient without undesirable consequences. The threshold may be, but
is not limited to, about 10 ppm or below about 50 milligrams of
solvent per 3.5 liters of fluid. 4. Example of Use
As described above, the delipidation device depicted schematically
in FIG. 11 is capable of removing at least a portion of a total
concentration of lipids from a fluid or from lipid-containing
organisms, or both. In this particular example, the fluid used was
bovine plasma. The bovine plasma was sent to DTC 220 at a flow rate
of 15 mL/min where it contacted a first extraction solvent, which
was composed of about 60 percent DiPE and about 40 percent
n-butanol. The first extraction solvent was added to DTC 220 before
the introduction of plasma at a flow rate of about 200 mL/min.
Contacting the first extraction solvent with the plasma caused
lipids to separate from the plasma and to form a first mixture of
plasma and first extraction solvent. Similarly, lipids in
lipid-containing organisms may be removed by the first extraction
solvent.
The first mixture was then washed with a second extraction solvent,
which was diethyl ether (DEE), in a series of DTCs 236 250, which
were about 20 inches long and about 0.375 inches in diameter. The
process created a second mixture composed of the plasma and first
and second extraction solvents. At least a portion of the lipids
contained in the plasma was removed after passing the first mixture
only one time through the DTCs forming intermediate phase subsystem
14, which was observed as the initially turbid plasma becoming
clearer with a single pass through the DTCs containing DEE. In
addition, at least a portion of the n-butanol was removed. The flow
rate through the intermediate phase subsystem 14 was approximately
15 mL/min.
The second mixture was then introduced into a final phase subsystem
218 as shown in FIG. 10. The second mixture was circulated through
HFCs 160 and 162 at a flow rate of about 750 mL/min, wherein each
HFC had a holdup volume of about 50 mL and an area of about 4200
cm.sup.2. Air was circulated through the shells of HFCs 160 and 162
to extract the residual first extraction solvent from the fluid.
This process was continued until the solvent vapor detector 176
indicated that solvent levels were below a particular threshold
enabling the remaining solvent to be removed with a final pass
through the carbon bed 180. Upon indication that sufficient levels
of solvent were removed enabling the fluid to be returned to a
patient without undesirable effects, the fluid was then tested to
determine the effectiveness of this embodiment.
The process resulted in a reduction of cholesterol of about 90
percent, which was measured by standard lipid profile enzymatic
assays that are known in the art. For a volume of approximately 300
mL of plasma and using discontinuous subsystems emulating the
system described above, the delipidation process takes
approximately 20 minutes, thereby achieving a delipidation
throughput of about 15 mL/min.
C. Third Embodiment 1. General Description
FIG. 12 depicts a portion of another embodiment of delipidation
system 10 which includes initial phase subsystem and intermediate
phase subsystem. This embodiment may be used together with the
final phase subsystems shown in FIGS. 9 and 10 as described in more
detail below. Unlike the previous systems described above, this
embodiment does not use different apparatuses to complete the
initial and intermediate phases of the delipidation process.
Rather, this embodiment uses a single apparatus for completing the
initial and intermediate phases of the delipidation process.
Specifically, FIG. 12 depicts in-line static mixers 270 and 272
coupled to both inlet and outlet sides of a vortexer 274. In-line
static mixers 270 and 272 may be formed from many designs, but
typically include single or multiple tubes containing one or more
flow vanes along their length. Further, this embodiment is not
limited to two in-line static mixers, but may comprise any number
of in-line mixers coupled in series or parallel configuration, or
any combination of these configurations. The vanes cause mixing and
shearing of the fluids passed through the mixers. The amount of
mixing and shearing can be regulated by changing the flow rates of
the fluid through mixers 270 and 272. An example of in-line static
mixers 270 and 272 are available from Cole-Parmer Instrument
Company, Vernon Hills, Ill. as Catalog Part Number U-04668-14.
Vortexer 274 may be a continuous vortexer, as shown in FIG. 6, or a
batch vortexer, as shown in FIG. 7. Furthermore, the configuration
of this embodiment is not limited to the design shown in FIG. 12.
For instance, vortexer 274 may be positioned before in-line static
mixer 270 or after in-line static mixer 272. As previously
described, these vortexers operate upon receiving external
vibration that causes vortices to form in each tube. The
non-rotating vortexer 274 is advantageous because of its simplistic
design that is less expensive than more complicated designs. Thus,
it may be used more efficiently than other devices in a disposable
system. Further, vortexer 274 does not contain any bushings,
bearings or moving parts that are subject to failure.
In-line static mixer 270 receives a fluid from a fluid source 276
through valve 278 via gravity, a vacuum, a pump 280, or other
means. Prior to the fluid entering in-line static mixer 270, the
fluid mixes with a first extraction solvent at T-connection 282.
The first extraction solvent is supplied from a first extraction
solvent source 284 through valves 286 and 288 via gravity, pump
290, which may be a peristaltic pump, centrifugal pump, or other
type pump, or other means. First extraction solvent source 284
includes vent 292 for safe operation.
A centrifuge 294 may be positioned in-line down stream of in-line
static mixers 270 and 272 and vortexer 274. Centrifuge 294, as
shown in FIG. 8, is configured as a discontinuous flow-through
channel in the shape of a ring that is spun about its axis.
However, centrifuge 294 is not limited to this configuration.
Rather, centrifuge 294 may be any centrifuge. Centrifuge 294
separates the fluid from the first and second extraction
solvents.
During operation, a fluid is sent from fluid source 276 to in-line
static mixer 270. A first extraction solvent mixes with the fluid
at T-connection 282 prior to the fluid entering in-line static
mixer 276. The fluid and first extraction solvent pass through
in-line static mixers 270 and 272 and vortexer 274 where at least a
portion of the lipids contained within the fluid or in
lipid-containing organisms are separated and dissolve into the
first extraction solvent. The first mixture of first extraction
solvent and fluid passes through centrifuge 294 where the first
extraction solvent is separated from the fluid. The fluid is sent
back to valve 278, and the first extraction solvent separated from
the fluid is deposited in waste receptacle 296, which may include
vent 298, or circulated through condenser 300 to valve 288 to be
mixed with a fluid. The fluid may be sent through in-line static
mixers 270 and 272 one or more times during the initial phase.
The intermediate phase of the delipidation system 10 is conducted
using in-line static mixers 270 and 272 and vortexer 274.
Specifically, the first mixture composed of the fluid and residual
first extraction solvent not completely removed by centrifuge 294
is sent through T-connection 282 and mixes with a second extraction
solvent to form a second mixture. The second mixture solvent is
contained in a second extraction solvent source 302, which may
include a vent 304 for safe operation. The second mixture of and
first and second extraction solvents is sent through in-line static
mixers 270 and 272 and vortexer 274 where a portion of the first
extraction solvent may be removed. For example, in one embodiment
in which the first extraction solvent is a mixture of DiPE and
n-butanol, the second extraction solvent separates at least a
portion of the n-butanol from the mixture of first extraction
solvent and the fluid. The second extraction solvent may also
separate a portion of the lipids from the fluid not removed while
using the first extraction solvent. The separated lipids may
dissolve in the first or second extraction solvents, or both. The
second mixture is sent through centrifuge 294 where the fluid and
the first and second extraction solvents are separated. After
passing through centrifuge 294, the fluid contains small amounts of
first and second extraction solvents and is sent to final phase
subsystem 16 for removal of these remaining amounts of the first
and second extraction solvents. The first and second extraction
solvents are then sent to waste receptacle 296.
This embodiment may be used in cooperation with a subsystem capable
of removing at least a portion of the first and second extraction
solvents from the fluid after it has passed through initial and
intermediate phase subsystems. For example, this embodiment may be
combined with the once-through subsystem 99 shown in FIG. 9 or the
recirculating subsystem 218 shown in FIG. 10. Each of these
subsystems is explained in more detail in Sections III.A.3(a) and
(b) above. 2. Example of Use
As described above, the delipidation device depicted schematically
in FIG. 12 is capable of removing at least a portion of a total
concentration of lipids from a fluid containing lipids or from
lipid-containing organisms, or both. In this particular example,
bovine plasma was used as the fluid. The bovine plasma was
introduced to in-line static mixer 270, as shown for instance in
FIG. 12, at a flow rate of about 50 mL/min where it contacted a
first extraction solvent, which was composed of about 60 percent
DiPE and about 40 percent n-butanol. The first extraction solvent
was added to in-line static mixer 270 at a flow rate of about 50
mL/min. Contacting the first extraction solvent with the plasma
caused lipids to separate from the fluid and form a first mixture
of plasma and first extraction solvent. The first mixture was then
circulated through vortexer 274. The vortexer 274 had a capacity of
500 mL, and the centrifuge 294 had a capacity of 80 mL. The first
mixture was then sent through in-line static mixer 272. The first
mixture then circulated through centrifuge 294, which had a
relative centrifugal force (RCF) equal to about 560 times gravity
(560.times.g). Multiple passes through the circulation loop may be
required to achieve the desired delipidation result. Further, a
second extraction solvent may also be used, preferably a diethyl
ether (DEE) solvent, to achieve the desired amount of removal of a
first extraction solvent. Adding a second extraction solvent to the
first mixture forms a second mixture composed of the plasma and the
first and second extraction solvents.
The second mixture was then introduced into a final phase subsystem
as shown in FIG. 10. The second mixture was circulated through HFCs
160 and 162 at a flow rate of about 750 mL/min, wherein each HFC
had a holdup volume of about 50 mL and an area of about 4200
cm.sup.2. Air was circulated through the shells 172 and 174 of HFCs
160 and 162 to extract the residual first extraction solvent from
the fluid. This process was continued until the solvent vapor
detector 176 indicated that solvent levels were below a particular
threshold enabling the remaining solvent to be removed with a final
pass through the carbon bed 180. Upon indication that sufficient
levels of solvent were removed, the fluid was then tested to
determine the effectiveness of the apparatus.
The total percentage of lipid extracted as measured by reduction of
total cholesterol was about 80 percent, as measured by standard
lipid profile enzymatic assays that are known in the art. This
method can produce fluid having a reduced concentration of lipids
or lipid-containing organisms at a rate of about 50 mL/min. This
apparatus successfully removed about 85 percent of the total
concentration of cholesterol, about 64 percent of triglycerides,
about 64 percent phospholipids and about 96 percent high density
lipoproteins (HDL) using discontinuous subsystems emulating the
system described above.
D. Fourth Embodiment 1. General Description
FIG. 13 depicts a delipidation system 10 that is similar to the
embodiment shown in FIG. 12. However, in-line static mixers 270 and
272 and vortexer 274 have been replaced with HFC 310. While FIG. 13
shows a single HFC, the embodiment may include one or more HFCs
configured in parallel or in series, or in any combination thereof.
HFC 310 may be constructed as described above, including hollow
fibers 312 and a chamber 314, that is also referred to as the shell
side of hollow fibers 312. As in the embodiment shown in FIG. 12,
one apparatus is capable of performing the initial and intermediate
phases of delipidation.
HFC 310 receives a fluid containing lipids or lipid-containing
organisms, or both, from a fluid source 316, which may be a
container, patient or other fluid source, through valve 318 via
gravity, pump 320, or other means. Pump 320 may be a peristaltic
pump or other pump not having vanes that contact the fluid being
pumped. The fluid is sent through the lumens of hollow fibers 312
of HFC 310 to contact the fluid with a first extraction solvent.
The first extraction solvent is contained within a first extraction
solvent source 322 which may have vent 324 for safe operation. The
first extraction solvent is sent from first extraction solvent
source 322 through valves 326 and 328 via gravity, pump 330, which
may be a peristaltic pump, centrifugal pump or other type pump, or
other means.
The first extraction solvent crosses the pores of HFC 310 and
causes at least a portion of the lipids contained within the fluid
to separate. At least a portion of the separated lipids diffuse
through the pores of hollow fibers 312 and return to chamber 314.
However, some of the first extraction solvent that diffused the
pores into the lumens of hollow fibers 312 will remain in the fluid
to form a first mixture composed of the first extraction solvent
and the fluid. Further, a portion of the lipids that separate from
the fluid may attach to the inside surface of the lumens of hollow
fibers 312. The first extraction solvent located in chamber 314
flows through HFC 310 and valve 332 and into waste receptacle 334,
which may have a vent 336 for safe operation, or through condenser
342 to be used in HFC 310 once again. The first mixture of fluid
and first extraction fluid flows from the lumens into hollow fibers
312 through valve 338 and is returned to the upstream side of HFC
310.
The intermediate phase of the delipidation process may be conducted
by sending the mixture of fluid and the first extraction solvent
through the lumens of hollow fibers 312 of HFC 310 to contact a
second extraction solvent located in chamber 314. In one
embodiment, HFC 310 is the same HFC used in the initial phase. In
an alternative embodiment, HFC 310 may be replaced or reoriented so
that the flow through the lumens of hollow fibers 312 or chamber
314, or both, is reversed. The second extraction solvent is sent
from a second extraction solvent source 340 to chamber 314 of HFC
310 through valves 326 and 328 via gravity, a vacuum, pump 330, or
other means. At least a portion of the second extraction solvent
crosses the pores of hollow fibers 312 and mixes with the mixture
of fluid and first extraction solvent removing at least a portion
of a first extraction solvent. For example, in one embodiment in
which a first extraction solvent is a mixture of n-butanol and
DiPE, a second extraction solvent removes at least a portion of the
n-butanol from the mixture. The second extraction solvent may also
cause lipids to separate from the fluid. A portion of the separated
lipids may attach to the inside surface of hollow fibers 312 and a
portion of the separated lipids may dissolve in the second
extraction solvent and cross the pores of hollow fibers 312 into
chamber 314.
At the conclusion of the intermediate phase of the delipidation
process, the fluid contains a small amount of first and second
extraction solvents and is referred to as a second mixture. This
mixture is sent through valve 338 to a system capable of extracting
at least a portion of the second extraction solvent from the fluid
to reduce the concentration of this solvent to a level enabling the
fluid to be administered to a patient without potentially adverse
consequences. Examples of systems capable of removing the second
extraction solvents are the once-through subsystem 99, shown in
FIG. 9, and the recirculating subsystem 218, shown in FIG. 10, as
fully described above. However, this invention is not limited to
these embodiments.
This embodiment described above may be assembled in a module that
resembles module 306 depicted in FIGS. 18 and 19. The module
contains the components of delipidation system 10 through which the
fluid flows. In one embodiment, the module is disposable, which
enables the system to be set up quickly after having been used. The
device is prepared for use with another patient's fluid by simply
removing the module and replacing it with an unused sterile module
or a module that is sterilized following a prior use. 2. Method of
Operation
This embodiment combines a fluid, which preferably is plasma, and
at least one first extraction solvent. In this example, the first
extraction solvent may be composed of about 40 percent n-butanol
and about 60 percent di-isopropyl ether (DiPE). The fluid is mixed,
agitated or otherwise contacted with the first extraction solvent
to remove a portion of the lipids or lipid-containing organisms
from the fluid. A small batch of the plasma, which is typically
about 250 milliliters, is passed through the lumens of hollow
fibers 312 of HFC 310 at a flow rate of about 20 mL/min. HFC 310
provides a method of contacting the plasma with the first
extraction solvent while essentially keeping the two mixtures
separated. However, a portion of the first extraction solvent
crosses the pores of HFC 310 and does not return to the shell side
of hollow fibers 312 and thus forms a first mixture. The first
mixture is recirculated through HFC 310 at the same flow rate,
which is usually about 20 mL/min.
The first extraction solvent is then substantially removed from the
plasma before being administered to a patient. First, the flow of
plasma is stopped, and the first extraction solvent is removed from
the shell side of the HFC. A second extraction solvent is then sent
through the shell side of the hollow fibers of the HFC. The second
extraction solvent may be composed of about 100 percent isopropyl
ether, about 100 percent ethyl ether, or any other ether or
concentration of these ethers. Desirable properties of the ethers
include, but are not limited to, reduced toxicity, higher vapor
pressure, and a partition coefficient that is favorable with
n-butanol. The second extraction solvent does not recirculate as
does the first extraction solvent. Instead, the second extraction
solvent flows through HFC 310 only one time at a rate of about 40
mL/min. The first mixture is sent through HFC 310 multiple times at
a rate of about 20 mL/min for about 90 minutes. The second
extraction solvent crosses the membrane of the hollow fibers of the
HFC and mixes with the first mixture of plasma and first extraction
solvent to form a second mixture. In one embodiment in which the
first extraction solvent is a mixture of n-butanol and DiPE, the
second extraction solvent removes at least a portion of the
n-butanol from the first mixture. In addition, the second
extraction solvent may remove a portion of the remaining lipids
from the fluid. The second extraction solvent is then removed by,
for instance evaporating the second wash solvent from the plasma
using a pervaporation system, such as the subsystems shown in FIGS.
9 and 10.
E. Fifth Embodiment
FIG. 20 depicts another embodiment of delipidation system 10 that
includes initial, intermediate and final phase subsystems. Initial
phase subsystem 12 includes at least one vortexer 350 for mixing a
fluid containing lipids or lipid-containing organisms with a first
extraction solvent. Vortexer 350 may be a continuous vortexer as
shown in FIG. 6 or a batch vortexer as shown in FIG. 7. These
vortexers operate upon receiving external vibration that causes
vortices to form in each tube. The non-rotating vortexer 350 is
advantageous because of its simplistic design that is less
expensive than more complicated designs. Thus, it may be used more
efficiently than other devices in a disposable system. Further,
vortexer 350 does not contain any bushings, bearings or moving
parts that are subject to failure. However, vortexer 350 may be
formed from an alternative design. Initial phase subsystem 12 may
also include centrifuge 356, which may be configured as shown in 8
or may be configured in another manner.
Vortexer 350 receives a fluid containing lipids or lipid-containing
organisms from a fluid supply source 352 and mixes the fluid with a
first extraction solvent received from a first extraction solvent
source 354. Vortexer 350 forms a first mixture of first extraction
solvent and fluid. Vortexer 350 also causes lipids to separate from
the fluid or lipid-containing organisms. The lipids are removed and
discarded, and the first mixture is sent to intermediate phase
subsystem 14.
Intermediate phase subsystem 14 is composed of at least one HFC for
contacting the first mixture with a second extraction solvent to
remove at least a portion of the first extraction solvent from the
first mixture. FIG. 20 shows three HFCs 358, 360, and 362, which
may be configured as shown in FIGS. 3 and 4 and described in detail
above. The first mixture may be sent through lumens of HFCs 358,
360, and 362, and a second extraction solvent, supplied from second
extraction solvent source 355, may be sent through HFCs 358, 360,
and 362 on the shell side of the lumens, or vice versa. HFCs 358,
360, and 362 removes at least a portion of the first extraction
solvent from the first mixture and forms a second mixture of the
fluid containing lipids or lipid-containing organisms and the first
and second extraction solvents. The amount of surface area of
hollow fibers required and the amount of residence time required
for the fluid to reside in HFCs 358, 360, and 362 is calculated as
set forth above. In embodiments having two or more HFCs 354, HFCs
may be configures in parallel, series, any combination thereof, or
any other configuration.
Intermediate phase subsystem 14 passes a second mixture of fluid
and first and second extraction solvent to final phase subsystem
16. Final phase subsystem 16 removes substantially all of the
second extraction solvent and any remaining first extraction
solvent not removed in intermediate phase subsystem 14. Final phase
subsystem 16 may be composed of any system capable of removing
extraction solvents from a fluid containing lipids or
lipid-containing organisms. Exemplary systems are shown in FIGS. 10
and 11 and described in III.A..3 (a) and (b), respectively and
labeled as final phase subsystem 16 in FIG. 20. The embodiment
shown in FIG. 20 includes two HFCs 364 and 366 for removing at
least a portion of the first and second extraction solvents from
the second mixture. A material such as, but not limited to, air, an
inert gas, nitrogen and the like, or mineral oil may be circulated
through HFCs 364 and 366 on the shell side of the lumens and
through solvent removal subsystem 368. Solvent removal subsystem
may include a first sterile filter 370, a vacuum pump 372, a second
sterile filter 374, and one or more carbon beds 376.
F. Exemplary Embodiments
The embodiments described above may be manufactured so that all
components that come in contact with a fluid containing lipids or
lipid-containing organisms, or both, during operation are contained
within a single module that may be disposable. The first embodiment
described above may be assembled in a module 98, as depicted in
FIGS. 14 and 15. The second embodiment described above may be
assembled in a module 264, as depicted in FIGS. 16 and 17. The
third embodiment described above may be assembled in a module 306,
as depicted in FIGS. 18 and 19. Modules 98, 264 and 306 contain
components of delipidation system 10 through which the fluid flows.
To prevent the spread of diseases and for other health reasons, the
delipidation system 10 should be cleaned after each use before
being used with a fluid from a different source. In one embodiment,
modules 98, 264 and 306 are disposable, which enables the system to
be set up quickly after having been used. Delipidation device 10
may be prepared for use with another patient's fluid by simply
removing a module and replacing it with a sterile module that may
have never been used or may have been sterilized since a prior
use.
G. Experimental Results
A system having an initial, intermediate, and final phase
subsystems was employed. The initial phase subsystem was composed
of three HFCs manufactured by Celguard. The intermediate phase
subsystems was composed of three HFCs manufactured by Spectrum, and
the final phase subsystem was composed of two HFCs manufactured by
Celguard. All HFCs were oriented in series. Plasma was applied to
the lumens of the HFCs. In the initial phase subsystem, the shell
side of the HFCs contained a mixture of 40% butanol and 60% DIPE
flowing in the same direction as the plasma flowing through the
lumens of the HFCs at a rate of about 20 ml/min.
In the intermediate phase subsystem, 100 percent DiPE flowed
through the HFCs on the shell side of the lumens at a rate of 40 ml
per minute in a countercurrent direction to the direction of flow
of the plasma through the lumens of the HFCs. In the final phase
subsystem, air flowed through the three HFCs on the shell side of
the lumens. Clinical chemistry data characterizing the parameters
in the effluent delipidated plasma were obtained using a Hitachi
911. Results indicated dramatic reductions in cholesterol,
triglycerides and HDL. Very little change or no change was observed
in electrolytes (Na, Cl, and K), calcium, phosphorous, protein,
albumin, globulin, phospholipids, creatinine, BUN, glucose, and
alkaline phosphatase.
While various embodiments of this invention have been set forth
above, these descriptions of the preferred embodiment are given for
purposes of illustration and explanation. Variations, changes,
modifications, and departures from the systems and methods
disclosed above may be adopted without departure from the spirit
and scope of this invention.
* * * * *
References